Renu was sitting inside train A, which was travelling at 50 km/h. Another train, B whose length was three times the length of A crossed her in the opposite direction in 15 seconds. If the speed of train B was 58 km/h. Then the length of train A (in m) is:

A. 210

B. 180

C. 160

D. 150

Answer: Option D

Solution(By Examveda Team)

$$\eqalign{ & {\text{Lenth of train A}} = l \cr & {\text{Lenth of train B}} = 3l \cr & \frac{{3l}}{{\left( {50 + 58} \right) \times \frac{5}{{18}}}} = 15 \cr & \frac{{3l \times 18}}{{108}} = 15 \times 5 \cr & l = 150{\text{ m}} \cr} $$