Discussion

Question:

Two trains X and Y start from stations A and B towards B and A respectively. After passing each other, they take 4 hours 48 minutes and 3 hours 20 minutes to reach B and A respectively. If train X is moving at 45 km/h, the speed of train Y is:

Explanation:

Here $\frac{X' s speed}{Y' s speed}$ = $\sqrt{\frac{T i m e t a k e n b y Y t o r e a c h A a f t e r m e e t i n g}{T i m e t a k e n b y X t o r e a c h B a f t e r m e e t i n g}}$

⇒ $\frac{45}{Y' s speed}$ = $\sqrt{\frac{10 / 3}{24 / 5}}$ = $\frac{5}{4}$

⇒ Y's speed = 54 kmph

Hence, option (b).

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