Database-Management-System
January 9, 2024Question 6290 – CHENNAI MATHEMATICAL INSTITUTE – M.Sc. / Ph.D. Programme in Computer Science ( 15 May 2014 )
January 9, 2024Question 7538 – HCU PHD CS MAY 2017
Two motorists set out at the same time from A to B, a distance of 100 miles. They both followed the same route and travelled at different though uniform speeds of integral number of miles /hour. The difference in their speeds was a prime number of miles/hour. After they had been driving for 2 hrs, the distance of the slower car from A was five times that of the faster car from B. How fast did the motorists drive?
Correct Answer: B
Question 1 Explanation:
The two motorists:
Let d=the distance the faster car has traveled. Then it still has 100-d miles to go, and the slow car has, therefore, gone 500-5d miles. Let A and B be the rates of the fast and slow cars in mph. Then d/A = (500-5d)/B = 2
We get B=250-5B
Then A-B=6f-250
=(3A-125).
But since A-B is prime 3A-125=1
hence A=42mph and B=40 mph
Let d=the distance the faster car has traveled. Then it still has 100-d miles to go, and the slow car has, therefore, gone 500-5d miles. Let A and B be the rates of the fast and slow cars in mph. Then d/A = (500-5d)/B = 2
We get B=250-5B
Then A-B=6f-250
=(3A-125).
But since A-B is prime 3A-125=1
hence A=42mph and B=40 mph
30 and 37 miles/hour
40 and 42 miles/hour
47 and 49 miles/hour
None of the above