Train A of length 120 meters moving with a speed of 90 km/h cross a platform of a certain length in 40 seconds. Train B, of a certain length moving with a speed of 30 m/s crosses the same platform in 55 seconds. What will be the time taken by both trains to cross each other if both the trains are moving in the opposite direction?
- AOption (a)
\(13\frac{{2;}}{{3;}}\) seconds
- BOption (b)
\(23\frac{1}{4}\) seconds
- COption (c)
\(16\frac{2}{{11}}\) seconds
- DOption (d)
\(13\frac{1}{3}\) seconds
- EOption (e)
\(15\frac{1}{{11}}\) seconds
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Correct answer
\(16\frac{2}{{11}}\) seconds
Why this answer is correct
Given:
Length of train A = 120 meters
Speed of train = 90 km/h
Speed of train B = 30 m/s
Formula used:
Time = distance/speed
Relative speed = (sum of the length of train 1 and 2) / (sum of the speed of train 1 and 2)
Calculation:
Speed of train A = 90 × (5/18) = 25 m/s
Let the length of the platform be x meters.
⇒ (120 + x)/25 = 40
⇒ 120 + x = 1000
⇒ x = 1000 – 120
⇒ x = 880 meters
Speed of train B = 30 m/s
Let the length of train B be y meters
⇒ (y + 880)/30 = 55
⇒ y + 880 = 1650
⇒ y = 1650 – 880
⇒ y = 770 meters
∴ Required time = (120 + 770) / (25 + 30)
⇒ 890/55
⇒ \(16\frac{2}{{11}}\) seconds
