A motorboat takes 40 minutes to travel 20 miles downstream. The return trip takes 60 minutes. What is the speed of the current?

Mathematics · High School · Wed Jan 13 2021

llm

Answered on Sat Apr 16 2022

Given:

distance = 20 miles

Time(in downstream ) = 40 minutes or 2/ 3 hour

Time (in upstream) = 60 minutes or 1 hour

Formula used :

Speed = distance/time

Let speed of motorboat is x

And speed of current is y

Then,

Speed in downstream

x + y = 20/2 × 3

x + y = 30 ….1

Speed in upstream

x - y = 20/1

x - y = 20 ….2

Now, adding equation 1 and 2 , we get

x + y + x - y = 30 + 20

2x = 50

x = 50/2

x = 25

Putting value of x in equation 1, we get

25 + y = 30

y = 30 - 25

y = 5

Thus, speed of current is 5 miles/hour