A boat travels miles upstream in hours and then returns the miles downstream in hours. If the boat's speed in still water and the current are both constant, what is the boat's speed in still water, in miles per hour?
Answer and explanation
Correct answer: D.
- Step 1: Find the upstream and downstream speeds: mph, and mph.
- Step 2: Set up the system with boat speed and current : and .
- Step 3: Add the two equations to solve for : mph.
Answer
.
Why not the others: represents the speed of the water current alone rather than the total effective downstream speed of the boat.
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