Averages

Question 1
A group of 210 students appeared in some test. The mean of 1/3 rd of students is found to be 60. The mean of the remaining students is found to be 78. The mean of the whole group will be:
A
80
B
76
C
74
D
72
Mathematical-ReasoningAverages2015 December NTA UGC NET Paper 1
Question 1 Explanation: 
Given data:
Total number of students = 210
1/3 rd of 210 = 70 students
Mean marks of 70 students = 60
To Find: Mean of the whole group= ?
Let the sum of marks of 70 students be X
Mean = X / Number of students
60 = X/70
X = 70*60

⇒ Sum of marks of 70 students = 4200
Remaining students = 210 - 70 = 140 students
Mean of 140 students = 78
Sum of marks of 78 students = 140*78 = 10920
Total marks of 210 students = 4200 + 10920
= 15120
Mean of whole group = 15120 / 210
= 72 marks
Question 2
In an examination 10,000 students appeared. The result revealed the number of students who have:
Passed in all five subjects = 5583
Passed in three subjects only = 1400
Passed in two subjects only = 1200
Passed in one subject only 735
Failed in English only = 75
Failed in Physics only = 145
Failed in Chemistry only = 140
Failed in Mathematics only = 200
Failed in Bio-science only = 157
The number of students passed in at least four subjects is:
A
7900
B
6300
C
6900
D
7300
Mathematical-ReasoningAverages2015 June NTA UGC Paper 1
Question 3
Anil played 8 cricket matches. The mean (average) of the runs was found to be 80. After playing four more matches, the mean of the runs of all the matches was found to be 70. The total runs made in the last four matches is
A
400
B
300
C
200
D
100
Mathematical-ReasoningAverages2016 August NTA UGC NET Paper 1
There are 3 questions to complete.

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