A is twice fast as B and B is thrice fast as C is. The journey covered by C in $$\frac{3}{2}$$ hours will be covered by A is:

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
$$\eqalign{ & = \frac{3}{{2 \times 6}} \cr & = \frac{1}{4}\,\,{\text{hours}} \cr & = 15\,\,{\text{minutes}} \cr} $$