a man can row a bangka at a rate of 5 km/h in still water. It takes 10 minutes longer to row upstream a distance of 2km than he takes to row downstream. What is the rate of the current?
let rate of the stream be x km/h
So speed with the current = 5+x
speed against the current = 5-x
2/(5-x) - 2/(5+x) = 10/60
times ((5-x)(5+x)
2(5+x) - 2(5-x) = (1/6)(25 - x^2)
4x = (1/6)(25-x^2)
24x = 25-x^2
x^2 + 24x - 25 = 0
(x+25)(x-1) = 0
x = 1 or x = a negative, which we will reject
the current has a rate of 1 km/h