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notka56 [123]
3 years ago
7

The speed of the current is 7 mph. The boat travels three times slower against the current than with the current. What is the sp

eed of the boat in still water?
Mathematics
1 answer:
kotykmax [81]3 years ago
3 0
Let the speed of the boat be x
so going against the current the speed is x-7
going with the current the speed is x+7

let the distance be d
time = distance / speed
time to go against the current = d/(x-7)
time to go with the current = d/(x+7)

time going against the current is 3 times going <span>with the current
</span>
d/(x-7) = 3d/(x+7)     ⇒⇒⇒ divide by d 
1/(x-7) = 3/(x+7) 
x+7 = 3(x-7) 
x+7 = 3x - 21
2x = 28
x = 14

So, the speed of the boat in still water is = 14 mph
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