1)

Without stoppage a train travels certain distance with an average speed of 80 km/h and with stoppages, it covers the same distance with an average speed of 60 km/h. How many min per the train stops ?

A) 10 min

B) 12 min

C) 15 min

D) 20 min

E) 30 min

Stoppage (time/h) = $\frac{Change\quad in\quad speed }{Faster\quad Speed}$
$=\frac{(80-60)}{80}$ $=\frac{1}{4}$