Question

A navy boat goes 50 miles downstream in 2 1/2 hours. Going upstream, it traveled the same distance in 4 hours. What is the rate of the boat in still water, and what is the rate of the current?

a) Boat rate: 20 mph, Current rate: 10 mph
b) Boat rate: 15 mph, Current rate: 10 mph
c) Boat rate: 10 mph, Current rate: 15 mph
d) Boat rate: 10 mph, Current rate: 5 mph

Answer 1

The rate of the boat in still water is 12.5 mph and the rate of the current is 7.5 mph.

Step-by-step explanation:

The rate of the boat in still water can be found by taking the average of the downstream rate and the upstream rate. In this case, the boat traveled 50 miles downstream in 2 1/2 hours, so the downstream rate is 50 miles / 2.5 hours = 20 mph. The boat also traveled the same distance upstream in 4 hours, so the upstream rate is 50 miles / 4 hours = 12.5 mph.

To find the rate of the current, we can subtract the upstream rate from the rate in still water. So, the rate of the current is 20 mph - 12.5 mph = 7.5 mph.

Therefore, the rate of the boat in still water is 12.5 mph and the rate of the current is 7.5 mph. The correct answer is option d) Boat rate: 10 mph, Current rate: 5 mph.