Question

A man can row a boat at 20 km per hour in still water if the speed of stream in 6 km per hour what is the time taken to draw a distance of 60 km downstream

Answer 1

in downstream

speed =speed in still water +speed of stream
20km per h +6 km per h = 26 km per h

distance = 60 km
time = distance / speed
60 km/ 26 km per h
2.3 h
so, time taken is 2.3 h

Answer 2

CONCEPT:

Speed of the water in downstream=speed of the water in still+ speed of stream.

speed of the journey=distance covered / total time taken

from this the total time for the journey= total distance covered/speeed of the journey

GIVEN:

speed for sailing boat in still water= 20km/hour

speed of stream=6km/hour

FIND:

time taken to cover a distance of 60 km downstream

SOLUTION:

Speed of the water in downstream=20 km/h+6 km/h=26 km/hour

time taken =distance covered/speed of the journey

so total time required to cover the distance of 60 km=60/26=2.3  hours

so time taken to draw a distance of 60 km downstream is 2.3 hours

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