Excluding stoppages the speed of a bus is 54

Excluding stoppages, the speed of a bus is 54 kmph and including stoppages, it is 45 kmph. For how many minutes does the bus stop per hour?

A. 10 min

B. 9 min

C. 8 min

D. 7 min

Answer:

A. 10 min

Explanation:

L.C.M. of 54 and 45 = 270

$\therefore$ Time taken by bus to cover 270 km excluding stoppages =54270​=5hours

Time taken by bus to cover 270 km including stoppages =45270​=6hours

$\therefore$ Time for which the bus stops per hour =66−5​hours=61​×60min=10min.