SOLUTION: A Jet Ski rider can travel 16 miles against the current of the lower Mississippi River in 1/2 hour and make the return trip with the current in 1/3 hour. Find the speed of the Jet

Algebra ->  Percentage-and-ratio-word-problems -> SOLUTION: A Jet Ski rider can travel 16 miles against the current of the lower Mississippi River in 1/2 hour and make the return trip with the current in 1/3 hour. Find the speed of the Jet       Log On


   

Question 521817: A Jet Ski rider can travel 16 miles against the current of the lower Mississippi River in 1/2 hour and make the return trip with the current in 1/3 hour. Find the speed of the Jet Ski in still water and the speed of the current.
mph (jet ski in still water)?
mph (current)?
Answer by oberobic(2304) About Me  (Show Source):
You can put this solution on YOUR website!
d = r*t is the basic distance equation: distance = rate * time
.
d = 16 miles
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r = j - c when going upstream
j -c = jetski speed minus current speed
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r = j+c when going downstream
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t = 1/2 hr going upstream
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16 = 1/2*(j-c)
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t = 1/3 hr going downstream
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16 = 1/3(j+c)
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16=16
so
1/2*(j-c) = 1/3*(j+c)
(j-c)/2 = (j+c)/3
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Cross multiply
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3(j-c) = 2(j+c)
3j -3c = 2j + 2c
j = 5c
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substitute
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16 = 1/2*(5c-c)
32 = 4c
4c = 32
c = 8
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Substitute
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j = 5c
j = 40
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Check distances traveled in the given times to determine if this answer is correct.
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1/2*(40-8) = 16
1/3*(40+8) = 16
Correct.
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Answer: The speed of the jetski in still water is 40 mph, and the speed of the current is 8 mph.