Question

Anya was rowing up the river and noticed it takes longer to row upstream than downstream. She knows that in still water she can row 9 mph. She timed herself rowing approximately 4 miles upstream and then back in 1.5 hours. She then calculated the current of the river.

Answer 1

If the speed of boat in still water iss 9 mph and takes 1.5 miles to go and come 4 miles uptream and downward then the current of the river is 9.24 mph.

Given that the speed in still water be 9 mph, time to travel 4 miles upstream and downward is 1.5 hours.

We are required to find the speed of current of the river.

let the speed of current be c mph.

Effective speed in downstream=9+c

Effective speed in upstream=9-c

Total time=1.5 hours.

Total distance=4 miles.

Time for upstream stream+ time for downward stream=1.5 hours

2/(9+c)+2/(9-c)=1.5

18-2c+18+2c=1.5(9+c)(9-c)

36=1.5(81-$c^{2}$)

36=121.5-1.5$c^{2}$

1.5$c^{2}$=121.5-36

$c^{2}$=85.5

c=9.24 mph.

Hence the speed of the current of the river is 9.24 mph.

Learn more about speed at brainly.com/question/4931057

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