Marcus rowed 20 miles downstream in 2 hours. The trip back, however, took him 4 hours. Find the rate that Marcus rows in still water and the rate of t

geduiwelh

geduiwelh

Answered question

2021-01-27

Marcus rowed 20 miles downstream in 2 hours. The trip back, however, took him 4 hours. Find the rate that Marcus rows in still water and the rate of the current. If x is Marcuss

Answer & Explanation

wornoutwomanC

wornoutwomanC

Skilled2021-01-28Added 81 answers

From given,
Downstream equation is: Distance 20, Rate x + y, Time 2
Upstream equation is: Distance 20, Rate x  y, Time 4
It is that, the distance formula is D=RT.
That implies,
20=4(xy)
20=2(x+y)
Thus, the downstream equation is 2x+2y=20 (1)
The upstream equation is 4x4y=20 (2)
Multiply equation (1) by 2 and add it with (2)
4x+4x=40+4x4y=20
=8x=60
x=608
x=7.5
The rate that Marcus rows in still water and the rate of the curent 7.5 mph
The speed of the river current is,
4(7.5)4y=20
304y=20
4y=2030
4y=10
y=2.5
Thus, the speed of the river current is 2.5 mph

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