This is on my homework and just wondering how to work this problem. These word problems are very confusing for me.

Question

Left on together, the cold and hot water faucets of a certain bathtub take 5 minutes to fill the tub. If it takes the cold water faucet 15 minutes to fill the tub by itself, how long will it take the hot water faucet to fill the tub on its own

Answer 1

Hi Blake,

 

First we can find the amount that each faucet can do in one minute

 

Cold = 1/15    (it takes 15 minutes so it will fill 1/15 each minute

Hot = 1/x       (this is what we want to find

 

t = time to fill the tub with both = 5

 

5(1/15) + 5(1/x) = 1             (where 1 represents the full tub

 

(1/3) + (5/x) = 1

 

5/x = 2/3                       (subtract 1/3 from each side of the equation

 

2x = 15                           (cross mutiply

 

x = 7.5

 

so it will take the hot ware faucet 7.5 minutes on its own

 

Hope this helps