Question

a motorboat whose speed in still water is 5 km per hour takes 1 hour more to go 12 km upstream then the return downstream to the same spot find the speed of the stream

Answer 1

let speed of stream be x kmph
upstream speed of boat 5-x kmph
downstream speed of boat 5+x kmph
$\frac{12}{5 - x} - \frac{12}{5 + x} = 1 \\ \frac{12(5 + x) - 12(5 -x )}{(5 + x)(5 - x)} = 1 \\ \frac{60 + 12x - 60 + 12x}{25 - {x}^{2} } = 1 \\ 24x = 25 - {x}^{2} \\ - {x}^{2} - 24x + 25 = 0 \\ {x}^{2} + 24x - 25 = 0 \\ {x}^{2} + 25x - x - 25 = 0 \\ x(x + 25) - 1(x + 25) = 0 \\ (x + 25)(x - 1) = 0 \\ x = - 25 \: \: \: discard \: it \\ x = 1$
speed of stream is 1 kmph

Answer 2

Answer:

1 km/hr

Step-by-step explanation:

follow the attachment