Question

a motorboat whose speed in still water is 18 km per hour takes 1 hour more to go 24 km upstream then to return downstream to the same Spot. Find the speed of the stream

Answer 1

24/18-x - 24/18+x = 1
324-x^2 = 48x
x^2 +48x-324= 0
x^2+54x - 6x -324=0
(x^2+54x)-(6x+324)=0
x(x+54)-6(x+54)=0
x=6 kmph

Answer 2

Answer:

Let the speed of stream be x km / hr

For upstream = ( 18 - x ) km / hr

For downstream = ( 18 + x ) km / hr

A.T.Q.

24 / 18 - x - 24 / 18 + x = 1

48 x = 324 - x²

x² + 48 x - 324 = 0

( x + 54 ) ( x - 6 ) = 0

x = - 54 or x = 6

Since speed can't be negative .

Therefore , speed of the stream is 6 km / hr .