Question

An experienced employee can enter tax data into a computer tree times as fast as a new employee. Working together, it takes them 9hrs. How long would it take the experienced employee working alone?

Answer 1

12 hours

Explanation:

Let x hours be the time needed for the experienced employee, then 3x hours is time needed for the new employee.

Then, the experienced employee completes
`(1)/(x)` of the whole work per hour and the new employee completes
`(1)/(3x)` of the whole work per hour.

Altogether the can complete

`(1)/(x)+(1)/(3x)=(4)/(3x)`

of the whole work per hour and need

`(1)/((4)/(3x))=(3x)/(4)`

hours to finish the whole work.

Working together, it takes them 9 hours, then

`(3x)/(4)=9\\ \\3x=36\\ \\x=12\ hours`