Question

A motorboat whose speed in still water is 18 km/ h, takes 1 hour more to go 24 km upstream than to return downstream to the same spot. Find the speed of the stream ?​

Answer 1

Solution :-

• The speed of a motor boat in still water = 18km/h
• Let the speed of the motorboat be s

Formula to be used in this question :-

★Speed of upstream = speed of downstream + 1

=> 24/18-s = 24/18+s

=> 24(18+s) = 24(18-s) + (18-s) + (18+s)

=> s² + 48s - 324 = 0

=> s² + 54s + 6s = 0

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

=> s = 6 or -54.

Therefore, the speed of the stream is 6km/h because the speed of the stream can be negative.