two pipes filling a pool. how many hours does it take?

Question

A pool can be filled by one pipe in 6 hours and by a second pipe in 5.  How long will it take to fill the pool using both pipes?

Answer 1

Hi Kathelyn,

 

If one pipe can fill it in 6 hours then if fills 1/6 of the pool each hour

 

the other fills 1/5 of the pool each hour

 

let x = time it takes together

 

x(1/5) + x(1/6) = 1   Where 1 represents the pool being filled

 

multiply both sides of the equation by 30 to get rid of the denominator

 

6x + 5x = 30

 

11x = 30

 

x =30/11   

 

this would be about 2 hours and 43.64 minutes

 

Hope this helps