Question

a boat goes 6 km upstream and back again to the starting point in 2 hours.com if speed of the current is 4km/h . what is the speed of the boat in still water ?​

Answer 1

Step-by-step explanation:

Dist =6km, let the distance of boat in still water is X km/h , time = 2 h

Upstream = x-y , downstream = x+y

Time = dist/speed

2 = 6/ x-y + 6/x+y

1 = 3{1/x-y + 1/ x+y }

1= 3{ x+ y + x - y/(x+y)(x-y)}

1= 3 {2x/(x+y)(x-y)}

Putting Y = 4

6x =( x+4)(x-4)

X^2–6x - 16=0

X^2 - 8x +2x -16=0

X( x - 8) +2 (x-8) =0

X= 8 km/h