Question

If Joanne can paint a room in 3 hours and her sister Angela can paint the same room in 4 hours, how long (in h) would it take Joanne and Angela to paint the room working together? Round to the nearest tenth.

Answer 1

Explanation:

If J can paint a room in 3 hours, in 1 hour she gets
`(1)/(3)` of the job done.

If A can paint a room in 4 hours, in 1 hour she gets
`(1)/(4)` of the job done. We need to find out how long it takes them if they paint together. The equation for this is:

`(1)/(3)+(1)/(4)=(1)/(x)` where x is the number of hours it takes them to get the job done together. Multiply everything through by 12x to get

4x + 3x = 12 so

7x = 12 and

x = 1.7 hours to get the room painted together.