Question

down
A man can row a boat with 4 kmph in still water. He is crossing a river where these
is 2 kmph. The time taken by him to row 2 km upstream is
A bo
A) 2 hr
B) 1 hr
C) 4 hr
D) 3 hr
km​

Answer 1

Answer:

4/3 hrs

Explanation:

Given :

Velocity of man wrt water,

VMW=4 km/hr

Velocity of river, V

R=2 km/hr

Distance covered in upstream or downward motion d=2 km each

For upstream motion of the boat :

Velocity of the man ,

Vm =VMW −VW =4−2=2 km/h

∴ Time taken to go upstream

t1 = 2/2 =1 hr

For downward motion of the boat or (return journey) :

Velocity of the man VM=Vmw +Vw

=4+2=6 km/h

∴ Time taken to go downstream

t2= 2/6

=1/3 hr

∴ Total time taken

T=t1+ t2= 1+1/3

= 4/3 hr