GATE 2015 [Set3]
Question 1 
Extreme focus on syllabus and studying for tests has become such a dominant concern of Indian students that they close their minds to anything _____ to the requirements of the exam
related  
extraneous  
outside  
useful 
Question 2 
A function f(x) is linear and has a value of 29 at x = 2 and 39 at x = 3. Find its value at x = 5.
59  
45  
43  
35 
Question 3 
The Tamil version of ________ John Abrahamstarrer Madras café ________ cleared by the Censor Board with no cuts last week but the film’s distributors _________ no takers among the exhibitors for a release in Tamil Nadu _________ this Friday.
Mr., was, found, on  
a, was, found, at  
the, was, found, on  
a, being, find at 
Question 4 
If ROAD is written as URDG, then SWAN should be written as:
VXDQ  
VZDQ  
VZDP  
UXDQ 
S+3 = V, W+3 = Z, A+3 = D, N+3 = Q.
Question 5 
Select the pair that best expresses a relationship similar to that expressed in the pair: Children: Pediatrician
Adult: Orthopedist  
Females: Gynecologist  
Kidney: Nephrologist  
Skin: Dermatologist 
Question 6 
The exports and imports (in crores of Rs.) of a country from the year 2000 to 2007 are given in the following bar chart. In which year is the combined percentage increase in imports and exports the highest?
2006  
2007  
2008  
2009 
Increase in imports in 2006 = 120  90/90 = 33.3% which is more than any other year.
Question 7 
The head of a newly formed government desires to appoint five of the six selected members P, Q, R, S, T and U to portfolios of Home, Power, Defense, Telecom, and Finance. U does not want any portfolio if S gets one of the five. R wants either Home or Finance or no portfolio. Q says that if S gets either Power of telecom, then she must get the other one. T insists on a portfolio if P gets one Which is the valid distribution of portfolios?
PHome, QPower, RDefense, STelecom, TFinance  
RHome, SPower, PDefense, QTelecom, TFinance  
PHome, QPower, TDefense, STelecom, UFinance  
QHome, UPower, TDefense, RTelecom, PFinance 
Question 8 
Choose the most appropriate equation for the function drawn as a thick line, in the plot below
x = y  y  
x = (y  y)  
x = y + y  
x = (y + y) 
Then the Answer is x =  (y  y)
Question 9 
Most experts feel that in spite of possessing all the technical skills required to be a batsman of the highest order, he is unlikely to be so due to lack of requisite temperament. He was guilty of throwing away his wicket several times after working hard to lay a strong foundation. His critics pointed out that until he addressed this problem, success at the highest level will continue to elude him. Which of the statements(s) below is/are logically valid and can be inferred from the above passage?
 (i) He was already a successful batsman at the highest level.
(ii) He has to improve his temperament in order to become a great batsman.
(iii) He failed to make many of his good starts count.
(iv) Improving his technical skills will guarantee success.
(iii) and (iv)  
(ii) and (iii)  
(i), (ii) and (iii)  
(ii) only 
→ He is unlikely due to lack of requisite temperament  (ii) is True
→ He was guilty of throwing away his wicket several times  (iii) is True
Question 10 
Alexander turned his attention towards India, since he had conquered Persia. Which one of the statements below is logically valid and can inferred from the above sentence?
Alexander would not have turned his attention towards India had he not conquered Persia  
Alexander was not ready to rest on his laurels, and wanted to march to India  
Alexander was completely in control of his army and could command it to move towards India  
Since Alexander’s kingdom extended to Indian borders after the conquest of Persia, he was keen to move further 
Y be " he had conquered Persia"
Like that
∼X be "Alexander would not have turned his attention towards India"
then
∼Y be "he had not conquered Persis"
Answer is option A.
Question 11 
In a room there are only two types of people, namely Type 1 and Type 2. Type 1 people always tell the truth and Type 2 people always lie. You give a fair coin to a person in that room, without knowing which type he is from and tell him to toss it and hide the result from you till you ask for it. Upon asking, the person replies the following:
“The result of the toss is head if and only if I am telling the truth.”
Which of the following options is correct?
The result is head  
The result is tail
 
If the person is of Type 2, then the result is tail  
If the person is of Type 1, then the result is tail 
Case 1:
The person who speaks truth. This definitely implies that result of toss is Head.
Case 2:
The person who lies. In this the reality will be the negation of the statement.
The negation of (x⇔y) is exactly one of x or y holds. "The result of the toss is head if and only if I am telling the truth". So here two possibilities are there,
→ It is head and lie spoken.
→ It is not head and truth spoken.
Clearly, the second one cannot speaks the truth. So finally it is head.
Hence, option (A).
Question 12 
Consider the relation X(P, Q, R, S, T, U) with the following set of functional dependencies
F = { {P, R} → {S,T}, {P, S, U} → {Q, R} }
Which of the following is the trivial functional dependency in F+ is closure of F?
{P,R}→{S,T}  
{P,R}→{R,T}  
{P,S}→{S}  
{P,S,U}→{Q} 
Question 13 
Given a hash table T with 25 slots that stores 2000 elements, the load factor α for T is ___________.
80  
70  
60  
50 
Question 14 
Consider a software project with the following information domain characteristic for calculation of function point metric.

Number of external inputs (I) = 30
Number of external output (O) = 60
Number of external inquiries (E) = 23
Number of files (F) = 08
Number of external interfaces (N) = 02
It is given that the complexity weighting factors for I, O, E, F and N are 4, 5, 4, 10 and 7, respectively. It is also given that, out of fourteen value adjustment factors that influence the development effort, four factors are not applicable, each of he other four factors have value 3, and each of the remaining factors have value 4. The computed value of function point metric is __________.
612.06  
612.07  
612.08  
612.09 
Question 15 
Consider the following statements.

I. TCP connections are full duplex.
II. TCP has no option for selective acknowledgment.
III. TCP connections are message streams.
Only I is correct  
Only I and III are correct  
Only II and III are correct  
All of I, II and III are correct 
Question 16 
Suppose U is the power set of the set S = {1, 2, 3, 4, 5, 6}. For any T ∈ U, let T denote the number of element in T and T' denote the complement of T. For any T, R ∈ U, let TR be the set of all elements in T which are not in R. Which one of the following is true?
∀X ∈ U (X = X')  
∃X ∈ U ∃Y ∈ U (X = 5, Y = 5 and X ∩ Y = ∅)  
∀X ∈ U ∀Y ∈ U (X = 2, Y = 3 and X \ Y = ∅)  
∀X ∈ U ∀Y ∈ U (X \ Y = Y' \ X') 
(A) False. Consider X = {1,2}. Therefore, X' = {3,4,5,6}, X = 2 and X' = 4.
(B) False. Because for any two possible subsets of S with 5 elements should have atleast 4 elements in common. Hence X∩Y cannot be null.
(C) False. Consider X = {1,4}, Y= {1,2,3} then X\Y = {4} which is not null.
(D) True. Take any possible cases.
Question 17 
Among simple LR (SLR), canonical LR, and lookahead LR (LALR), which of the following pairs identify the method that is very easy to implement and the method that is the most powerful, in that order?
SLR, LALR  
Canonical LR, LALR  
SLR, canonical LR  
LALR, canonical LR 
Question 18 
Consider the following array of elements. 〈89, 19, 50, 17, 12, 15, 2, 5, 7, 11, 6, 9, 100〉. The minimum number of interchanges needed to convert it into a maxheap is
4  
5  
2  
3 
→ Swap 100 & 15
→ Swap 100 & 50
→ Swap 89 & 100
∴ Total 3 interchanges are needed.
Question 19 
The maximum number of processes that can be in Ready state for a computer system with n CPUs is
n  
n^{2}  
2^{n}  
Independent of n 
Maximum number of processes that will be in ready state is independent of number of processors.
Question 20 
While inserting the elements 71, 65, 84, 69, 67, 83 in an empty binary search tree (BST) in the sequence shown, the element in the lowest level is
65  
67  
69  
83 
Question 21 
Consider the following relation
Cinema (theater, address, capacity)
Which of the following options will be needed at the end of the SQL query
SELECT P1. address FROM Cinema P1
Such that it always finds the addresses of theaters with maximum capacity?
WHERE P1.capacity >= All (select P2.capacity from Cinema P2)  
WHERE P1.capacity >= Any (select P2.capacity from Cinema P2)  
WHERE P1.capacity > All (select max(P2.capacity) from Cinema P2)  
WHERE P1.capacity > Any (select max(P2.capacity) from Cinema P2) 
So the theaters which are having maximum capacity will satisfy the condition.
Question 23 
Consider the following C program segment.
# includeint main( ) { char s1[7] = "1234", *p; p = s1 + 2; *p = '0' ; printf ("%s", s1); }
What will be printed by the program?
12  
120400  
1204  
1034 
p now points to third element in s1, i.e., '3'.
*p = '0', will make value of '3' as '0' in s1. And finally s1 will become 1204.
Question 24 
The number of 4 digit numbers having their digits in nondecreasing order (from left to right) constructed by using the digits belonging to the set {1, 2, 3} is _____.
15  
16  
17  
18 
1 1 1 1
1 1 1 2
1 1 1 3
1 1 2 2
1 1 2 3
1 1 3 3
1 2 2 2
1 2 2 3
1 2 3 3
1 2 3 3
1 3 3 3
2 2 2 2
2 2 2 3
2 2 3 3
2 3 3 3
3 3 3 3
Hence, total 15 4digit no. are possible.
Question 25 
In the given matrix, one of the eigenvalues is 1. the eigenvectors corresponding to the eigenvalue 1 are
⎡ 1 1 2 ⎤ ⎢ 0 1 0 ⎥ ⎣ 1 2 1 ⎦
{α(4,2,1)  α≠0, α∈R}  
{α(4,2,1)  α≠0, α∈R}  
{α(2,0,1)  α≠0, α∈R}  
{α(2,0,1)  α≠0, α∈R} 
AX = λX ⇒ (A  I)X = 0
⇒ y+2z = 0 and x+2y = 0
⇒ y = 2z and x/(2) = y
∴ x/(2) = y = 2z ⇒ x/(4) = y/2 = z/1 = α(say)
∴ Eigen vectors are {α(4,2,1  α≠0, α∈R}
Question 26 
Consider a machine with a byte addressable main memory of 2^{20} bytes, block size of 16 bytes and a direct mapped cache having 2^{12} cache lines. Let the addresses of two consecutive bytes in main memory be (E201F)_{16} and (E2020)_{16}. What are the tag and cache line address (in hex) for main memory address (E201F)_{16}?
E, 201  
F, 201  
E, E20  
2, 01F 
No. of cache lines in cache is 2^{12} bytes which needs 12 bits. So next lower 12 bits are line indexing bits.
And the remaining top 4 bits are tag bits (out of 20). So answer is (A).
Question 27 
The result evaluating the postfix expression 10 5 + 60 6 / * 8  is
284  
213  
142  
71 
→ '5' is pushed in the stack
→ '+' comes so addition will be done by popping the top two elements in the stackand the result is pushed back into the stack, i.e., 10+5 = 15
→ 60 pushed in the stack
→ 6 pushed in the stack
→ '/' comes. So, 60/6 = 10
→ '*' comes. So, 15 * 10 = 150
→ '8' comes, push in the stack
→ '' comes. So, 1508 = 142
So the final result is 142.
Question 28 
Consider a CSMA/CD network that transmits data at a rate of 100 Mbps (10^{8} bits second) over a 1 km (kilometer) cable with no repeaters. If the minimum frame size required for this network is 1250 bytes, what is the signal speed (km/sec) in the cable?
8000  
10000  
16000  
20000 
B = 100 Mbps
d = 1 km
v = ?
In CSMA/CD, L = 2×d/v×B
⇒ v = 2dB/L = 2×10^{3}×10^{8}/10^{4}
⇒ v = 20,000 km/sec
Question 29 
Consider a software program that is artificially seeded with 100 faults. While testing this program, 159 faults are detected, out of which 75 faults are from those artificially seeded faults. Assuming that both are and seeded faults are of same nature and have same distribution, the estimated number of undetected real fault is _____ .
175  
176  
177  
178 
Question 30 
Consider a binary tree T that has 200 leaf nodes. Then, the number of nodes in T that have exactly two children are ____.
199  
198  
197  
196 
Question 31 
Let L be the language represented by the regular expression Σ*0011Σ* where Σ = {0,1}. What is the minimum number of states in a DFA that recognizes (complement of L)?
4  
5  
6  
8 
So, 5 states are there.
Question 32 
If for nonzero x, where a≠b then is
af(x) + bf(1/x) = 1/x  25  (1)
Put x = 1/x,
af(1/x) + bf(x) = x  25  (2)
Multiply equation (1) with 'a' and Multiply equation (2) with 'b', then
abf(1/x) + a^{2} = a/x  25a  (3)
abf(1/x) + b^{2} = bk  25b  (4)
Subtract (3)  (4), we get
(a^{2}  b^{2}) f(x) = a/x 25a  bx + 25b
f(x) = 1/(a^{2}  b^{2}) (a/x  25a  bx +25b)
Now from equation,
Hence option (A) is the answer.
Question 33 
Consider the following grammar G.
S → F ⎪ H F → p ⎪ c H → d ⎪ c
Where S, F and H are nonterminal symbols, p, d and c are terminal symbols. Which of the following statement(s) is/are correct?
 S1: LL(1) can parse all strings that are generated using grammar G.
S2: LR(1) can parse all strings that are generated using grammar
Only S1  
Only S2  
Both S1 and S2  
Neither S1 nor S2 
For first production,
So, there is 'c' common in both the first(s) in the production of S. So not LL(1).
For LR(1),
Since RR conflict is present. So, not LR(1).
Hence, Option (D) is the correct answer.
Question 34 
Consider the following partial Schedule S involving two transactions T1 and T2. Only the read and the write operations have been shown. The read operation on data item P is denoted by read(P) and the write operation on data item P is denoted by write(P).
T2 must be aborted and then both T1 and T2 must be restarted to ensure transaction atomicity  
Schedule S is nonrecoverable and cannot ensure transaction atomicity  
Only T2 must be aborted and then restarted to ensure transaction atomicity  
Schedule S is recoverable and can ensure atomicity and nothing else needs to be done 
Question 35 
Consider a B^{+} tree in which the search key is 12 bytes long, block size is 1024 bytes, record pointer is 10 bytes long and block pointer is 8 bytes long. The maximum number of keys that can be accommodated in each nonleaf node of the tree is ____ .
50  
60  
70  
80 
k(8) + (k1)12 ≤ 1024
20k ≤1036
k ≤ ⌊1036/20⌋ ⇒ k ≤ 51
As the order is 51, maximum we can store 50 keys.
Question 36 
Suppose X_{i} for i = 1, 2, 3 are independent and identically distributed random variables whose probability mass functions are Pr[X_{i} = 0] = Pr[X_{i} = 1]=1/2 for i = 1, 2, 3. Define another random variable Y = X_{1}X_{2} ⊕ X_{3}, where ⊕ denotes XOR. Then Pr[Y = 0X_{3} = 0] = _______________.
0.75  
0.76  
0.77  
0.78 
Pr(Y=0/ X_{3}=0) = Pr(Y=0 ∩ X_{3}=0)/ Pr(X_{3}=0)
= 3/8 / 4/8 = 3/4 = 0.75
Question 37 
The total number of prime implicants of the function f(w,x,y,z) = Σ(0, 2, 4, 5, 6, 10) is ______.
3  
4  
2  
1 
Total 3 prime implicants are there.
Question 38 
Consider the following recursive C function. If get(6) function is being called in main() then how many times will the get() function be invoked before returning to the main()?
void get (int n){ if (n < 1) return; get(n1); get(n3); printf("%d", n); }
15  
25  
35  
45 
Question 39 
Assume that a mergesort algorithm in the worst case takes 30 seconds for an input of size 64. Which of the following most closely approximates the maximum input size of a problem that can be solved in 6 minutes?
256  
512  
1024  
2048 
where c is some constant
It is given that for n = 64,
cn log n = 30
c × 64 log 64 = 30
c × 64 × 6 = 30
c = 5/64
Now, the value of n for
c n log n = 360
5/64 × n log n = 360
n log n = 360×64/5
= 72 × 64 = 2^{9} × 9
So for n = 2^{9}, it satisfies.
So, n = 2^{9} = 512
Question 40 
The velocity v (in kilometer/minute) of a motorbike which starts from rest, is given at fixed intervals of time t(in minutes) as follows:
t 2 4 6 8 10 12 14 16 18 20 v 10 18 25 29 32 20 11 5 2 0
The approximate distance (in kilometers) rounded to two places of decimals covered in 20 minutes using Simpson’s 1/3rd rule is _________.
309.33  
309.34  
309.35  
309.36 
∵v = velocity
= 2/3[(0+0)+4(10+25+32+11+2)+2(18+29+20+5)]
= 309.33 km
(Here length of each of the subinterval is h = 2)
Question 41 
Consider the following C program.
# include int main( ) { static int a[] = {10, 20, 30, 40, 50}; static int *p[] = {a, a+3, a+4, a+1, a+2}; int **ptr = p; ptr++; printf("%d%d", ptr  p, **ptr}; }
The output of the program is _________.
140  
150  
160  
170 
**ptr = 40
∴ printf (“%d%d”, p + r – p, p + r) will print 140.
Question 42 
Consider the following policies for preventing deadlock in a system with mutually exclusive resources.
 I. Processes should acquire all their resources at the beginning of execution. If any resource is not available, all resources acquired so far are released.
II. The resources are numbered uniquely, and processes are allowed to request for resources only in increasing resource numbers.
III. The resources are numbered uniquely, and processes are allowed to request for resources only in decreasing resource numbers.
IV. The resources are numbered uniquely. A process is allowed to request only for a resource with resource number larger than its currently held resources.
Which of the above policies can be used for preventing deadlock?
Any one of I and III but not II or IV  
Any one of I, III, and IV but not II  
Any one of II and III but not I or IV  
Any one of I, II, III, and IV 
Question 43 
Let G be a connected undirected graph of 100 vertices and 300 edges. The weight of a minimum spanning tree of G is 500. When the weight of each edge of G is increased by five, the weight of a minimum spanning tree becomes __________.
995  
996  
997  
998 
Question 44 
If the following system has nontrivial solution,
 px + qy + rz = 0
qx + ry + pz = 0
rx + py + qz = 0
then which one of the following options is True?
pq+r = 0 or p = q = r  
p+qr = 0 or p = q = r  
p+q+r = 0 or p = q = r  
pq+r = 0 or p = q = r 
Question 45 
Consider a network connected two systems located 8000 kilometers apart. The bandwidth of the network is 500 × 10^{6} bits per second. The propagation speed of the media is 4 × 10^{6} meters per second. It is needed to design a GoBackN sliding window protocol for this network. The average packet size is 10^{7} bits. The network is to be used to its full capacity. Assume that processing delays at nodes are negligible. Then the minimum size in bits of the sequence number field has to be ___________.
8  
7  
6  
5 
n = ?
∴a=T_{p}/T_{n} =2/0.02=100
Given Protocol, GobackN protocol, So η = w/(1+2a) where w = 2^{n}1
100/100 = w/(1+2a) ⇒ w = 1+2a
⇒ 2^{(n1)} = 1+2(100)
⇒ 2^{n}  1 = 201
⇒ 2^{n} = 202 ⇒ 2^{n} = 2^{8}
⇒ n = 8
Question 46 
Language L1 is polynomial time reducible to language L2. Language L3 is polynomial time reducible to L2, which in turn is polynomial time reducible to language L4. Which of the following is/are True?
 I. If L4 ∈ P, L2 ∈ P
II. If L1 ∈ P or L3 ∈ P, then L2 ∈ P
III. L1 ∈ P, if and only if L3 ∈ P
IV. If L4 ∈ P, then L1 ∈ P and L3 ∈ P
II only  
III only  
I and IV only  
I only 
L_{1} ≤ pL_{2}
If L_{4} ∈ P then L_{2} ∈ P hence L_{1} ∈ P, hence option C.
Question 47 
Consider the following reservation table for a pipeline having three stages S1, S2 and S3.
Time >  1 2 3 4 5  S1  X     X  S2   X   X   S3    X   
The minimum average latency (MAL) is ________.
3  
5  
6  
7 
S1 is needed at time 1 and 5, so its forbidden latency is 51 = 4.
S2 is needed at time 2 and 4, so its forbidden latency is 42 = 2.
So, forbidden latency = (2,4,0) (0 by default is forbidden)
Allowed latency = (1,3,5) (any value more than 5 also).
Collision vector (4,3,2,1,0) = 10101 which is the initial state as well.
From initial state we can have a transition after "1" or "3" cycles and we reach new states with collision vectors
(10101 >> 1 + 10101 = 11111) and (10101 >> 3 + 10101 = 10111) respectively.
These 2 becomes states 2 and 3 respectively.
For "5" cycles we come back to state 1 itself.
From state 2 (11111), the new collision vector is 11111.
We can have a transition only when we see first 0 from right.
So, here it happens on 5th cycle only which goes to initial state. (Any transition after 5 or more cycles goes to initial state as we have 5 time slices).
From state 3 (10111), the new collision vector is 10111.
So, we can have a transition on 3, which will give (10111 >> 3 + 10101 = 10111) third state itself. For 5, we get the initial state.
Thus all the transitions are complete. State\Time 1 3 5 1 (10101) 2 3 1 2 (11111)   1 3 (10111)  3 1 So, minimum length cycle is of length 3 either from 33 or from 13. So the minimum average latency is also 3.
Question 48 
In the network 200.10.11.144/27, the fourth octet (in decimal) of the last IP address of the network which can be assigned to a host is ____________.
158  
157  
156  
155 
Subnet mask is 255.255.255.224
Do AND with given IP and subnet mask then we get NID 200.10.11.128
In fourth octet first three bit will fixed for subnet and remaining 5 bits is for HID, so maximum value as 11111.
The address with all 1s in host part is broadcast address and can't be assigned to a host.
So the maximum possible last octal in a host IP is 10011110 which is 158.
Question 49 
Which of the following languages are contextfree?
 L1 = {a^{m}b^{n}a^{n}b^{m} ⎪ m, n ≥ 1}
L2 = {a^{m}b^{n}a^{m}b^{n} ⎪ m, n ≥ 1}
L3 = {a^{m}b^{n} ⎪ m = 2n + 1}
L_{1} and L_{2} only  
L_{1} and L_{3} only  
L_{2} and L_{3} only  
L_{3} only 
L_{2}: First push all the a's in the stack then push all the b's in the stack. Now again a's come which cannot be compared by previous a's in the stack because at top of the stack's there are b's which is also needed to be pushed for further comparison with the next b's. So not CFL.
L_{3}: First simply read one 'a', then push one 'a' in the stack after reading two a's and then pop all the a's by reading the b's. Since can be done by PDA hence CFL.
Question 50 
Consider the following C program:
# includeint main( ) { int i, j, k = 0; j = 2 * 3 / 4 + 2.0 / 5 + 8 / 5; k = j; for (i = 0; i < 5; i++) { switch(i + k) { case 1: case 2: printf("n%d", i + k); case 3: printf("n%d", i + k); default: printf("n%d", i + k); } } return 0; }
The number of times printf statement is executed is __________.
10  
11  
12  
13 
= 6 / 4+2.0 / 5+1;
= 1 + 0.4 + 1
= 2.4
But since j is integer,
j=2
Now,
k = k  (j)
k = 0  (1) = 1
When i=0, i+k = 1,
printf executed 1 time
When i=1, i+k = 0,
printf executed 1 time
When i=2, i+k = 1,
printf executed 3 times
When i=3, i+k = 2,
printf executed 3 times
When i=4, i+k = 3,
printf executed 2 times
∴ Total no. of times printf executed is,
1 + 1 + 3 + 3 + 2 = 10
Question 51 
Consider the following C program. The output of the program is __________.
# includeint f1(void); int f2(void); int f3(void); int x = 10; int main() { int x = 1; x += f1() + f2() + f3() + f2(); pirntf("%d", x); return 0; } int f1() { int x = 25; x++; return x; } int f2( ) { static int x = 50; x++; return x; } int f3( ) { x *= 10; return x; }
230  
240  
250  
260 
f1( ) = 25 + 1 = 26
f2( ) = 50 + 1 = 51
f3( ) = 10 × 10 = 100
f2( ) = 51 × 1 = 52 (Since here x is static variable so old value retains)
∴ x = 1+26+51+100+52 = 230
Question 52 
Consider the following code sequence having five instructions I1 to I5. Each of these instructions has the following format.
OP Ri, Rj, Rk
where operation OP is performed on contents of registers Rj and Rk and the result is stored in register Ri.
I1 : ADD R1, R2, R3 I2 : MUL R7, R1, R3 I3 : SUB R4, R1, R5 I4 : ADD R3, R2, R4 I5 : MUL R7, R8, R9
Consider the following three statements:
S1: There is an antidependence between instructions I2 and I5. S2: There is an antidependence between instructions I2 and I4. S3: Within an instruction pipeline an antidependence always creates one or more stalls.
Which one of above statements is/are correct?
Only S1 is true  
Only S2 is true  
Only S1 and S3 are true  
Only S2 and S3 are true 
S2: True. There is WAR dependency between I_{2} and I_{4}.
S3: False. Because WAR or antidependency can be resolved by register renaming.
Question 53 
Two hosts are connected via a packet switch with 10^{7} bits per second links. Each link has a propagation delay of 20 microseconds. The switch begins forwarding a packet 35 microseconds after it receives the same. If 10000 bits of data are to be transmitted between the two hosts using a packet size of 5000 bits, the time elapsed between the transmission of the first bit of data and the reception of the last bit of the data in microseconds is _______.
(1575)  
(1576)  
(1577)  
(1578) 
Bandwidth of the each link is 10^{7} bits/sec.
Given that propagation delay between host to switch and switch to host is same i.e. 20 microseconds.
Given that 35 microseconds of buffering time is required by the switch.
Total data we need to send is 10000 bits.
Given that packet size is 5000 bits.
Number of packets we need to send is 10000/5000 = 2 packets.
Total time for the first packet to reach from source to switch = Transmission time + propagation time
Transmission time=(5000 bits)/(10^{7} bits/sec) = 500 microseconds
Total time between source to switch is = 500 + 20 = 520 microseconds
Time required for the packet to reach from switch to destination is = Buffer time+Transmission time + propagation time = 35 + 500 + 20 = 555 microseconds.
Total time required for the first packet to reach to destination from the source = 520 + 555 =1075 microseconds.
While transferring first packet from switch to destination source starts sending of it's second packet to switch, that means from 1055 microsecond on wards transmission of 2nd packet is started by the source.
By the time first packet is reached to the destination 2nd packet is completely available at the switch.
Time required for the 2nd packet to reach to the destination from the switch is
= transmission time + propagation time = 500+20 = 520 microseconds
Therefore total time required for the two packets to reach to destination from the source = 1055+ 520 = 1575 microseconds.
Question 54 
Let R be a relation on the set of ordered pairs of positive integers such that ((p,q),(r,s)) ∈ R if and only if p  s = q  r. Which one of the following is true about R?
Both reflexive and symmetric  
Reflexive but not symmetric  
Not reflexive but symmetric  
Neither reflexive nor symmetric 
∴(p,q) R (p,q)
⇒ R is not reflexive.
Let (p,q) R (r,s) then ps = qr
⇒ rq = sp
⇒ (r,s) R (p,q)
⇒ R is symmetric.
Question 55 
For the processes listed in the following table, which of the following scheduling schemes will give the lowest average turnaround time?
First Come First Serve  
Nonpreemptive Shortest Job First  
Shortest Remaining Time  
Round Robin with Quantum value two 
FCFS:
TAT for A = completion time(A)  AT(A) = 3  0 = 3
TAT of B = 9  1 = 8
TAT of C = 13  4 = 9
TAT of D = 15  6 = 9
∴ Avg. TAT = 29/4
SJF:
TAT of A = 3  0 = 3
TAT of B = 9  1 = 8
TAT of C = 15  4 = 11
TAT of D = 11  6 = 5
∴ Avg. TAT = 27/4
SRTF:
TAT of A = 3  0 = 3
TAT of B = 15  1 = 14
TAT of C = 8  4 = 4
TAT of D = 10  6 = 4
∴ Avg. TAT = 25/4
RR:
TAT of A = 5  0 = 5
TAT of B = 15  1 = 14
TAT of C = 13  4 = 9
TAT of D = 11  6 = 5
∴ Avg. TAT = 33/4
∴ SRTF has lowest Avg. TAT.