A is twice as fast as B and B is thrice as fact as C

Home » Aptitude » Speed, Time and Distance » Question

A is twice as fast as B and B is thrice as fact as C is . The journey covered by C in 42 minute, will be covered by A in ?

1. 14 min
2. 28 min
3. 63 min
4. 7 min

Correct Option: D

Let C' s speed = x km/hr.
Then, B's speed = 3x km/hr.
and A's speed = 6x km/hr.

∴ Ratio of speed of A, B, C
= 6x : 3x : x = 6 : 3 : 1

Ratio of times taken = 1/6 : 1/3 : 1 or 1 : 2 : 6

∵ 6 : 1 : : 42 : t
⇒ 6t = 42
⇒ t = 7 min.