Question

if sarah and tim work together use 4 hours to finish a project, tim use 6 hours to complete the project alone, how long will sarah finish project alone?

Answer 1

She will finish in 12 hours.

Step-by-step explanation:

∵ The time taken by Sarah and Tim when they work together = 4 hours,

∴ The one day work of both Sarah and Tim =
`(1)/(4)`

Now, time taken by Tim when he works alone = 6 hours,

So, his one day work =
`(1)/(6)`

Thus, the one day work of Sarah = Their combined work - one day work of Tim

`=(1)/(4)-(1)/(6)`

`=(3-2)/(12)`

`=(1)/(12)`

Hence, the time taken by Sarah when she works alone =
`\frac{1}{\text{her one day work}}`

`=(1)/(1/12)`

= 12 days.