Solve the problem.
-The speed of a stream is $4 \mathrm{mph}$. If a boat travels 40 miles downstream in the same time that it takes to travel 20 miles upstream, what is the speed of the boat in still water?
A) $12 \mathrm{mph}$
B) $8 \mathrm{mph}$
C) $15 \mathrm{mph}$
D) $14 \mathrm{mph}$

Question

Quizplus · Accepted Answer

Let the speed of the boat in still water be $x \mathrm{mph}$. Downstream speed is $x + 4$ and upstream speed is $x - 4$. The time for both trips is the same, so $\frac{40}{x+4} = \frac{20}{x-4}$. Solving this equation gives $x = 12$.

Solve the Problem 4mph4 \mathrm{mph}4mph If a Boat Travels 40 Miles Downstream in the \mathrm{mph}

Solve the Problem $4 \mathrm{mph}$ If a Boat Travels 40 Miles Downstream in the \mathrm{mph}