Question

Mr Khanna also take his grandson for morning walk daily Mr Khanna cross a bridge in 7.5 minutes at his average speed of 2 km per hour if the grandson cross the bridge in 4 minutes find his average speed in kilometre per hour

Answer 1

length of bridge= speed(m/s)*time(s)
= 5/9*450 m=250m
time taken by grandson=4min=240s
length of bridge=250m
his speed= d/t= 250/240*18/5
=15/4 km/h

Answer 2

Answer:

length of bridge= speed(m/s)*time(s)

= 5/9*450 m=250m

time taken by grandson-4min=240s

length of bridge=250m

his speed= d/t= 250/240*18/5

= 15/4 km/h