Question

Amanda can proofread 17 reports in an hour, while Sally can proofread 28 reports in an hour. If they have 420 reports to proofread, how much time will it take between the two of them?

Answer 1

`9.33\ hours` or
`9\ hours\ and\ 20\ minutes`[/tex]

Explanation:

We know that Amanda can proofread 17 reports in an hour, while Sally can proofread 28 reports in an hour, then the number of reports they can proofread in an hour (together) is:

`17\ (reports)/(hour)+28\ (reports)/(hour)=45\ (reports)/(hour)`

So, together, they can proofread a total of 45 reports per hour.

Since they have 420 reports to proofread, we need to make the following division in order to calculate how much time will it take between the two of them to proofread 420 reports:

`time=(420\ reports)/(45\ (reports)/(hour))\\\\time=9.33\ hours` or
`9\ hours\ and\ 20\ minutes`

Answer 2

9 hours and 20 minutes.

Explanation:

In one hour, Amanda can proofread 17 reports.

In one hour, Sally can proofread 28 reports.

That means together, they can proofread 45 reports in one hour.

So we need to divide the total amount of reports by how much they can read in an hour:

420/45 = 28/3 = 9 1/3

The time it takes between the two of them is 9 hours and 20 minutes.