A is twice fast as B and B is thrice fast as C is. The journey covered by C in 3/2 hours will be covered by A is:

Answer: Option A

Let speed of C = X
Then Speed of B = 3X
Then Speed of A = 6X
Ratio of the speed of A and C = 1 : 6
So, Greater the speed less time taken in journey.
C’s speed is 6 times less than A So A will take $$\frac{1}{6}$$ of the total time taken C to covered same distance.
So, Time taken by A
$$\begin{array}{rl}& =\frac{3}{2\times 6}\\ & =\frac{1}{4}\text{hours}\\ & =15\text{minutes}\end{array}$$