Question

Maria can fill a certain order in 13 hours and Jim needs 15 hours to do the same job. Working together, how long will it take them to fill the order?

Answer 1

7 hours

Explanation:

Maria can fill a certain order in 13 hours,

so her working rate is

`(1)/(13)`

and Jim needs 15 hours to do the same job, so his working rate is:

`(1)/(15)`

Assuming the two will take x hours working together, then

`(1)/(13) + (1)/(15) = (1)/(x)`

`(28)/(195) = (1)/(x)`

`x = (195)/(28)`

`x = 6.96`

It will take both approximately 7 hour