A boat can go 180 miles downstream in the same time it can go 120 miles upstream. The speed of the current is 4 miles per hour. Find the speed of the boat in still water.
A) $16 \mathrm{mph}$
B) $24 \mathrm{mph}$
C) $30 \mathrm{mph}$
D) $20 \mathrm{mph}$

Question

Quizplus · Accepted Answer

The speed of the boat in still water can be found using the formula $v = \frac{d}{t}$, where $v$ is the speed, $d$ is the distance, and $t$ is the time. Let $x$ be the speed of the boat in still water. The speed downstream is $x + 4$ mph, and the speed upstream is $x - 4$ mph. Since the times are equal, we have $\frac{180}{x + 4} = \frac{120}{x - 4}$. Solving this equation for $x$ gives $x = 20$ mph.

A Boat Can Go 180 Miles Downstream in the Same 16mph16 \mathrm{mph}16mph

A Boat Can Go 180 Miles Downstream in the Same $16 \mathrm{mph}$