Respuesta :
If the speed of the stream is x
Time is given by d/r , where r is the rate and d is the distance;
Rate for upstream = (15-x) mph and that of down stream is (15 +x) mph
The time taken will be the same;
Thus; 2/(15-x) = 4/(15+x)
cross multiplying;
30 +2x = 60 -4x
6x = 30
x =5
Therefore the rate of the river is 5 mph
Time is given by d/r , where r is the rate and d is the distance;
Rate for upstream = (15-x) mph and that of down stream is (15 +x) mph
The time taken will be the same;
Thus; 2/(15-x) = 4/(15+x)
cross multiplying;
30 +2x = 60 -4x
6x = 30
x =5
Therefore the rate of the river is 5 mph
Answer:
The rate of the current is 5 mph.
Step-by-step explanation:
Given : Kellen's boat travels 15 mph. If she can travel 2 mi upstream in the same amount of time she can go 4 mi downstream.
To find : The rate of the river current ?
Solution :
Let x be the rate of the currents .
The downstream speed is 15+x.
The upstream speed is 15-x.
We know that, [tex]\text{Time}=\frac{\text{Distance}}{\text{Speed}}[/tex]
Upstream time = Downstream time
[tex]\frac{2}{15-x} =\frac{4}{15+x}[/tex]
Cross multiply,
[tex]2(15+x)=4(15-x)[/tex]
[tex]30+2x=60-4x[/tex]
[tex]6x=30[/tex]
[tex]x=\frac{30}{6}[/tex]
[tex]x=5[/tex]
Therefore, the rate of the current is 5 mph.
