Question 1109199
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In many problems like this, a fast way to the answer is to note that, for a fixed distance, the ratio of speeds is the reciprocal of the ratio of times.<br>
In this problem, the ratio of the upstream and downstream speeds is 8:12 = 2:3, so the ratio of times is 3:2.<br>
If the ratio of the times at the two speeds is 3:2 and the boat is rented for 5 hours, then you should go upstream for 3 hours and downstream for 2.<br>
3 hours upstream at 8mph is 24 miles; 2 hours downstream at 12mph is 24 miles.<br>
So you can go 24 miles upstream from the resort before you turn back; that takes 3 hours, so if you started at 7am you need to turn around and head back at 10am.