a 1000 L tank now contains 240 L of water. How long will it take to fill the tank using a pump that pumps 25 L per minute?

Question

There are three steps to the answer,

1) a let statement

2) an equation

3) an answer sentence.

Answer 1

 

What you have is:

240L 

You need to add 1000L -240L = 760L

You have a pump that pumps 25L/minute

 

Let t = the time in minutes it takes to add 760L of water to the tank.

 

(25L/minute)t = 760L is the equation or you can leave the 1000L in there and it would be:

(25L/minute)t +240L = 1000L

 

Divide both sides by 25L/minute to isolate the variable:

t = 760L/25L/minute

t = 760L*(minute/25L) ; dividing something by a fraction means multiplying by the reciprocal

t = 30.4 minutes

It will take 30.4 minutes to fill the tank to 1000L. .4 minutes is 24 seconds, therefore, it will take 30 minutes and 24 seconds to fill the tank to 1000L.