Question

Micah rows his boat on a river 4.48 miles downstream, with the current, in 0.32 hours. He rows back upstream the same distance, against the current, in 0.56 hours. Assuming his rowing speed and the speed of the current are constant, what is the speed of the current?

A) 3 miles per hour
B) 8 miles per hour
C) 11 miles per hour
D) 14 miles per hour

Answer 1

I might be wrong but i think its C 11 miles per hour.

Answer 2

Option: A is the correct answer.

A) 3 miles per hour.

Explanation:

Let the speed of boat in still water= u miles per hour

and speed of current=v miles per hour.

Micah rows his boat on a river 4.48 miles downstream, with the current, in 0.32 hours.

i.e. speed of the boat downstream is:

`Speed\ downstream=(4.48)/(0.32)\\\\i.e.\\\\Speed\ downstream=14`

( Since, the speed is the ratio of distance to time)

i.e.

u+v=14----------------(1)

Also,He rows back upstream the same distance, against the current, in 0.56 hours.

i.e. speed of boat upstream is:

`Speed\ upstream=(4.48)/(0.56)\\\\i.e.\\\\Speed\ upstream=8`

i.e.

u-v=8--------------(2)

Now, on adding equation (1) and (2) we get:

2u=22

i.e.

u=11 miles per hour

and putting the value of u back in equation (1) we have:

v=3 miles per hour

Hence, speed of current is: 3 miles per hour