Problema Solution

A boat was going upstream against a 5 mile per hour current. The boat trip took 10 minutes. On the return, it took 5 minutes. What is the speed of the boat in still water?

Answer provided by our tutors

Let speed of boat be x 

and speed of stream = 5 mile per hour 

Speed upstream = (x-5)

Speed down stream = (x+5)

Lets distance be y 

Speed = distance / time 

Distance = Speed * time 

y = (x-5)* (10/60)  [Upstream]

And y=(x+5)*(5/60) [down stream]

this implies 

(x-5)/6 =(x+5)/12

x-5=(x+5)/2

2x-10=x+5

x=15

hence speed of boat = 15 miles per hour .