Problema Solution
A boat travels 1km upstream and 1km back. The time for the round trip is 8hrs. The speed of the stream is 4 km/hr. The speed of the boat is how many km/hr.
Answer provided by our tutors
Speed of the boat = X km/hr (X>0)
Upstream speed = X - 4
Down stream speed = X + 4
because time = distance/velocity
=> [1/(X-4) + 1/(X+4)] = 8
=> X+4 + X -4 = 8(X2 - 16)
8X2 - 2X - 16 = 0
4X2 - X - 8 = 0
solve the quadratic equation
X = 1.5447 km/h