Question

Roy kayaked up the river and then back in a total time of 6 hours. The trip was 4 miles each way, and the current was difficult. If Roy kayaked at a speed of 5 mph, what was the speed of the current? Round your answer to the nearest tenth.

Answer 1

Just had this question on my quiz, the answer ended up being 4.3 mph

Answer 2

Answer:2.5 mph

Step-by-step explanation:

Total time for trip=6 hr

Speed of roy=5 mph

the trip 4 miles one side

Let v be the stream velocity

time=
`(distance)/(speed)`

`6=(4)/(5+v)+(4)/(5-v)`

`6=4\left [ (1)/(5-v)+(1)/(5+v)\right ]`

`1.5=\left [(5+v+5-v)/(\left ( 5+v\right )\left (5-v \right )) \right ]`

`75-3v^2=20`

`v=\sqrt{(55)/(3)}\approx 2.5mph`