Problem: Two cars race around a circular track in opposite directions at constant rates. They start at the same point and meet every 30 seconds. If they move in the same direction, they meet every 120 seconds. If the track is 1,800 meter long, what is the speed of each car?
View all: BANGLADESH BANK (BB) | ASSISTANT DIRECTOR (AD) | WRITTEN QUESTION SOLVE(MATH) | 2011
Correct Answer: The speed of the two cars 37.5 m/sec and 22.5 m/sec.
Explanation:
Suppose, the two cars are c1 and c2 respectively whose speed x1 m/sec and x2 m/sec respectively where x1 > x2
In the case of same direction:
30×1 + 30×2 = 1800 (Perimeter = 1800)
x1 + x2 = 60………… (i’)
Again, in the case of opposite direction: Circular Track
120×1—120×2=1800×1—x2 = 15————-(ii)
Now, from (i) -— (ii),
x1 = 37.5, and x2 = 22.5
