A boat running downstream cover a distance of 20 km in 5 hours while for covering the same distance upstream, it takes 4 hours. What is the speed of the boat in still water?

Options
- 4 km/hr
- 4.5 km/hr
- 5 km/hr
- None

CORRECT ANSWER : 4.5 km/hr

Discussion Board
Solution

Discussion Board
Solution

Given details ,
Distance of downstream D''''d = 20km
time of downstream = 5 hours
Distance of upstream D''''u = 20km
Time for upstreams= 4 hours
STEP 1 = Find speed of downstream and upstream first.
downstream speed S''''d = 20/5 = 4kmph
Upstream speed S''''u = 20/4= 5kmph
STEP 2 ,
Use the boat in still water formula that is 1/2× (downstream speed +upstream speed) and substitute it.

=1/2× {4+5}
=1/2 × (9)
= 4.5kmph
MAIL ME IF YOU HAVE ANY DOUBTS = gkaakash@yahoo.com

GK Aakash 07-30-2021 09:09 AM

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