SOLUTION: A boat can travel 16 kilometers per hour in still water. The boat travels 15 kilometers down a river and then 15 kilometers upstream. The entire trip takes 5.5 hours. What is the e

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Question 1012151: A boat can travel 16 kilometers per hour in still water. The boat travels 15 kilometers down a river and then 15 kilometers upstream. The entire trip takes 5.5 hours. What is the equation that describes the current,c, of the river?
A) ((5.5)/(15+c))+((5.5)/(15-c))=16
B) ((5.5)/(16+c))+((5.5)/(16-c))=15
C) ((16)/(15+c))+((16)/(15-c))=5.5
D) ((15)/(16+c))+((15)/16-c))=5.5
***I believe the answer is c but I want to make sure because i had trouble figuring it out*** Please help
Found 2 solutions by Boreal, ikleyn:
Answer by Boreal(15235) (Show Source):
You can put this solution on YOUR website!
c=current
trip downstream is 15 miles at (16+c) mph=15/(16+c) hr
trip upstream is 15 miles at (16-c) mph=15/(16-c) hr
Those two equal 5.5
It is D.
Multiply everything by (16+c)(16-c)
240-15c+240+15c=1408-5.5c^2
5.5c^2-928=0
The current is about 13 km/h
downstream at 29 km/h (about) takes just under a half hour.
upstream at 3 km/h takes about 5 hours.

Answer by ikleyn(52817) (Show Source):
You can put this solution on YOUR website!
.
A boat can travel 16 kilometers per hour in still water. The boat travels 15 kilometers down a river and then 15 kilometers upstream. The entire trip takes 5.5 hours. What is the equation that describes the current,c, of the river?
A) ((5.5)/(15+c))+((5.5)/(15-c))=16
B) ((5.5)/(16+c))+((5.5)/(16-c))=15
C) ((16)/(15+c))+((16)/(15-c))=5.5
D) ((15)/(16+c))+((15)/16-c))=5.5
***I believe the answer is c but I want to make sure because i had trouble figuring it out*** Please help
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The answer is D).

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