Correct Answer - Option 4 : 240 metres

**Given **

Speed of train = 72 km/hr

Time taken to cross platform = 30 seconds

**Formula Used **

Distance = Speed × Time

Distance = Length of train + Length of Platform

**Calculation **

According to the question

Length of train = 72 × (5/18) × 18 = 360 m

Length of train + Length of platform = 72 × (5/18) × 30

⇒ 360 + length of platform = 600

⇒ Length of Platform = 600 - 360 = 240 meters

**∴ The correct answer is 240 meters**