Question

A train moving at speed of 36 km/hr crosses a platform in 30 secs. If the length of platform is equal to 20% of length of train, then find the length of platform.  
1. 50 km
2. 300 m
3. 50 m
4. 30 m
5. 90 m

Answer 1

Correct Answer - Option 3 : 50 m

Given-

Speed of train = 36 km/hr

Time taken to cross the platform = 30 secs

Length of platform = 20% of length of train

Concept Used-

Distance = Speed × Time

Calculation- 

Speed of train = 36 km/hr

⇒ 36 × 5/18

⇒ 10 m/sec

Let the length of train = x

Length of platform = 20% of x

⇒ 0.2x

distance travelled by train  = 30 × 10

⇒ x + 0.2x  = 300

⇒ 1.2x = 300 

⇒ x = (10/12) × 300 = 250 m

so, length of platform = 0.2 × 250 = 50m

∴ Length of platform is 50 m