Solve.
-Jan swims at a speed of 4.9 mph in still water. The river she's in flows at a speed of 3.4 mph. How long will it take Jan to swim 1.3 mi downstream? Round your answer to the nearest tenth of an hour, if necessary.
A)0.9 hr
B)10.8 hr
C)0.2 hr
D)6.4 hr

Question

Quizplus · Accepted Answer

To solve this problem, we can use the formula:
time = distance / speed

Since Jan is swimming downstream (with the current), her effective speed will be the sum of her swimming speed and the speed of the river flow.

Effective speed downstream = swimming speed + river flow speed
= 4.9 mph + 3.4 mph
= 8.3 mph

Now we can use the formula to find the time it will take Jan to swim 1.3 miles downstream:

time = distance / speed
= 1.3 miles / 8.3 mph
≈ 0.1566 hours
≈ 0.2 hours (rounded to the nearest tenth of an hour)

Therefore, it will take Jan about 0.2 hours (or 12 minutes) to swim 1.3 miles downstream. The best choice is C. To solve this problem, we can use the formula: 
time = distance / (swim speed + river speed)

Substituting the given values, we get: 
time = 1.3 mi / (4.9 mph + 3.4 mph) = 0.2 hr

Rounding to the nearest tenth, we get the final answer of 0.2 hours, which is equivalent to approximately 12 minutes. Therefore, the best choice is C.

Solve. -Jan Swims at a Speed of 4.9 Mph in Still