CaptainLevi wrote:
In a 6 km long race, A beats B by 20 seconds, B beats D by 70 seconds and C beats D by 40 seconds. If the speed of A is 54 km/hr, by what distance does B beat C?
(A) 360 m
(B) 380 m
(C) 400 m
(D) 380 m
(E) 500 m
We are given the speed of A only.
Time taken by A to complete the race= Distance/Speed = 6 km / 54 km/hr = (1/9)*3600 sec = 400 sec
Time taken by B to complete the race is 20 sec extra because A beats B by 20 sec. So time taken by B = 420 sec
Time taken by D to complete the race is another 70 secs so D takes 490 secs
Time taken by C to complete the race is 40 secs less than D (because C beats D by 40 secs) = 450 secs
When distance travelled is same, time taken by B : time taken by C = 420 : 450 = 14:15
When time taken is same, distance travelled by B : Distance travelled by C = 15 : 14
The distance of 15 travelled by B is actually 6 km i.e. 6000 m. This means our multiplier is 400. So the difference of 1 between the distances they travelled is 400.
Answer (C)
For more on ratios, check:
https://www.veritasprep.com/blog/2011/0 ... of-ratios/
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Karishma
Veritas Prep GMAT Instructor
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