Question

One painter can paint a room in 2 hours; another painter requires 4 hours to paint

the same room. How long will it take them to paint the room together

Answer 1


`1(1)/(3)` hours

Explanation:

The first painter does
`(1)/(2)` (aka
`(2)/(4)`) the job in 1 hour.

The second painter does
`(1)/(4)` the job in 1 hour.

This means together they can do
`(3)/(4)` the job in 1 hour.

This means to do
`(1)/(4)` of the job they will need
`(1)/(3)` hours. (third of the work they do in an hour means they need a third of the time)

This means they need
`1(1)/(3)` hours to paint the room together.