It took a crew 4 h 48 min to row 4.4 km upstream and back again. If the rate of flow of the stream was 5 km/h,?

4h 48m = 4 + 48/60 = 4 4/5 = 24/5

Distance = velocity * time

time = distance / velocity

The rate of flow of the stream was 5 km/h

Velocity upstream = v - 5

Velocity downstream = v + 5

Time = time upstream + time downstream

24/5 = 4.4 /(v - 5) + 4.4 /(v + 5)

Use common denominator v^2 - 25

24/5 =( (4.4v + 22) + (4.4v - 22) ) / (v^2 - 25)

24/5 = 8.8v /(v^2 - 25)

(24/5)(v^2 - 25) = 8.8v = 44v/5

24v^2/5 - 44v/5 - 120 = 0

Solve using quadratic formula

(work not shown)

v = {-25/6, 6}

Disregard the negative root since the velocity cannot be negative

v = 6 km/h

m09072013