Question

Question #a4a8f

Answer 1

`4 " hours " 16 2/3 " minutes"`

Explanation:

If the printers are both working, the job will be done quicker.

Let's consider how much of the job each printer can do in `1` hour.

Printer 1: whole job done in `7` hours. In 1 hour `1/7` will be done.

Printer 2: whole job done in `11` hours. In 1 hour `1/11` will be done.

If the printers are working together, then in one hour they will finish:
`1/7 +1/11` of the total job.

`1/7 +1/11 = (11+7)/77`

=`18/77` of the full job `(77/77)`

the whole job will take `77/77 div 18/77`

`77/77 xx 77/18 = 77/18`

=`4 5/18` hours;

= `4 " hours " 16 2/3" minutes"`