math
posted by leila .
A motorboat can maintain a constant speed of 16 miles per hour relative to the water. The boat makes a trip upstream to a certain point in 20 minutes and the return trip takes 15 minutes. What is the speed of the current?

at what speed does current is in relative to water

let spped of current be X, when the boat goes upstream, the actual speed of boat= speed of boatspeed of current;when the boat goes downstream, the speed =speed of boat+speed of current
distance=speed x time
upstream: (16X)x 1/3
downstream:(16+X)x1/4
since the total distance of the trip doesnt change,
(16X)x 1/3=(16+X)x1/4
solve for x,
ps:the speed of boat is 16miles/hour,
dont forget to convert minutes into hour