A train moves in north direction with a speed of 54 km/hr. and a monkey running on the roof of the train, against its motion with a velocity of 18km/hr. with respect to the train, then the velocity of monkey as observed by a man standing on the ground:-

Answer

`B, t_(A)=165s, t_(B)=150 s`

Explanation

`V_(A)=(4+2)hat(i) +3 hat(j),V_(B)=(-3+2)hat(i) +4 hat(j)`

Time to cross the river `t_(A) =(100)/(3) ,t_(B)=(100)/(4)`
Drift `= (100)/(3) xx 6 = 200 m` , Drift `= -1 xx (100)/(4)`
Remaining distance `= 300 - 200 + 25 m`
`(t_("total"))_(A)=(100)/(3)+(100)/(8) ,t_(B)=(100)/(4)+(100)/(6)`
`t_(A)=(800+300)/(24)=(1100)/(24) ,t_(B)=(600+400)/(24)=(1000)/(24)`
`t_(A) = 165 sec t_(B)=150 sec`.