Question

a motorboat whose speed is 18 km per hour in still water takes 1 hour more to go up 24 km upstream then to return downstream to the same spot find the speed of the stream​

Answer 1

Answer:

LET SPEED = X

ACCORDING TO QUESTION

===> 24/ 18-X -  24/ 18+X = 1

===> (432 + 24X -432 + 24X)/ (18)²-(X)²= 1

===> 48X = 324 - X²

===> X²+48X-324 = 0

==> X²+54X - 6X - 324 = 0

==> X(X+54) -6(X+54) = 0

===> (X+54) (X-6) = 0

SO, X = 6 , -54(REJECTED)

ANSWER = 6KM/H

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 .