maths
posted by raghav on .
A boat goes 12 km upstream and 40 km downstream in 8 hours. It can go 16 km upstream and 32 km downstream is the same time. Find the speed of the boat in still water and the speed of the stream.

if the bot has speed b, and the stream has speed s, then since time=distance/speed,
12/(bs) + 40/(b+s) = 8
16/(bs) + 32/(b+s) = 8
b=6
s=2
check:
12/4 + 40/8 = 3+5 = 8
16/4 + 32/8 = 4+4 = 8