1)

Trains are running with speeds 30 km/h and 58 km/h in the same direction. A man in the slower train passes the faster train in 18 sec. The length in meters of the faster train is

A) 70 m

B) 100 m

C) 128 m

D) 140 m

E) 158 m

Relative Speed $=58-30$ $=28$ km/h
$=28\times\frac{5}{18}$ m/sec $=\frac{70}{9}$ m/sec
Length of the train $=\frac{70}{9}\times 15$ = 140 m