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

Question

dsp73

3 years ago

9

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:

svlad2 [7] · Answer 1 · 2022-05-31T10:38:47+03:00

Let
x--------> the speed of the boat in mph

we know that
going upstream the speed is x-7
going downstream the speed is x+7

let the distance be d
time to go upstream = d/(x-7) 
time to go downstream = d/(x+7)

time going upstream is 3 times going downstream
so
3d/(x+7) = d/(x-7) 
divide by d 
3/(x+7) = 1/(x-7) 
3x-21 = x+7 
2x = 28 
x = 14

the answer is
the speed of the boat in still water is 14 mph