Question

The distance from B to C is thrice that from A to B. Two trains travel from A to C via B. The speed of train 2 is double that of train 1 while traveling from A to B and their speeds are nterchanged while traveling from B to C. The ratio of the time taken by train 1 to that taken by train 2 in travelling from A to C is

• A. 1: 4
• B. 7: 5
• C. 5:7
• D. 4:1

Answer 1

Answer: (C)

5:7

Answer 2

Given,
Let the speed of train $1$ from $A$ to $B$ be $s$.
Then the speed of train $2$ from $A$ to $B$ is $2s$.
Time taken by train $1$ to cover $A$ to $C$ = $\frac{D}{s}+\frac{3D}{2s}=\frac{5D}{2s}$
And, time taken by train $2$ to cover $A$ to $C$
= $\frac{D}{2s}+\frac{3D}{s}=\frac{7D}{s}$
Required ratio = $\frac{5D}{2s}:\frac{7D}{2s} ⇒ 5:7$
So, the correct option is (C): $5:7$