Explanation:

Correct option 3: 54 Km/hr

Relative speed:

If two trains are traveling with speeds of magnitude u & v respectively, then the relative speed will be

u + v, if both trains are traveling in the opposite direction.

u - v, if both trains are traveling in the same direction.

Formula used:

Speed = distance/ times

Calculation:

Let the speed of train 1 (of length 200 m) is 'u' m/s & speed of train 2

(of length 150 m) be 'v' m/s.

Given that, the man is sitting in the second train & a train of length 200 meters across a man (here, 150 m is irrelevant data).

By using the above concept,

When both trains are traveling in the same direction,

u - v = 200/20

u - v = 10 -----(1)

When both trains are traveling in the opposite direction,

u + v = 200/10

u + v = 20 -----(2)

Adding both equations, we will get

2u = 30 or u =15 m/s

Since, 1 m/s = 3.6 km/hr

u = 15 × 3.6 = 54 km/hr

∴ The correct answer is 54 km/hr.