Choose the one alternative that best completes the statement or answers the question.

Solve the problem.
-The speed of a stream is 5 mph. If a boat travels 62 mi downstream in the same time that it takes to travel 31 mi upstream, what is the speed of the boat in still water?
A) 18 mph
B) 15 mph
C) 10 mph
D) 17 mph

Question

Choose the one alternative that best completes the statement or answers the question. 
 
Solve the problem.
-The speed of a stream is 5 mph. If a boat travels 62 mi downstream in the same time that it takes to travel 31 mi upstream, what is the speed of the boat in still water?
A) 18 mph
B) 15 mph
C) 10 mph
D) 17 mph

Quizplus · Accepted Answer

The speed of the boat in still water can be found by setting up the equation for time, where time = distance/speed. Let the speed of the boat in still water be x mph. Downstream, the boat's speed is (x + 5) mph, and upstream, it's (x - 5) mph. The time to travel downstream and upstream is the same, so we set the equations equal to each other: 62/(x + 5) = 31/(x - 5). Solving for x gives us 15 mph.

Choose the One Alternative That Best Completes the Statement or Answers