Question

Howie sorkin can travel 8 miles upstream in the same time it takes him to go 12 miles downstream. His boat goes 15 mph in still water. What is the rate of the current

Answer 1

Answer: the speed of the current is 2.5 mph

Step-by-step explanation:

Let the speed of the boat be x miles per hour

Let the speed of the current be y miles per hour

Speed = distance / time

Time = distance/speed

If the boat goes 12miles downstream(in still water) at 15 mph then, the time is

12/ 15 = 0.8 hours

In still water, it means that it moved in the same direction with the current.

The total speed would be x + y. Therefore

x + y = 15 - - - - - - -1

If the boat goes 8 miles upstream in 0.8 hours, the the speed is

8/ 0.8 = 10 miles per hour

Assuming it moved in the opposite direction to the current.

The total speed would be x -y. Therefore

x - y = 10 - - - - - - -2

Adding equation 1 and equation 2, it becomes

2x = 25

x = 25/2 = 12.5

y = 15 - x

y = 15 - 12.5 = 2.5 miles per hour