Question

A boat takes 8 hours to travel 30 km upstream and 36 km downstream; but it takes 10 hours to travel 36

km upstream and 48 km downstream. Find the speed of the boat in still water and the speed of the

stream.

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Answer 1

Answer:

Step-by-step explanation:let the speed of boat be x km/hr and speed of stream be y km/hr

speed of boat in upstream =x-y km/hr

speed of boat in downstream =x+y km/hr

by question,

30/x-y +36/x+y =8

36/x-y +48/x+y =10

let 1/ x-y=a

1/x+y=b

30a + 36b =8

36a + 48b =10

solving the 2 equations we get

a=1/6

and b=1/12

so 1/x-y=1/6

so,x-y=6

1/x+y=1/12

so,x+y=12

solving the 2 new equations we get x=9

and y=3

therefore,speed of boat is 9 km/hr and speed of stream is 3 km/hr