Question

If they work together. Mark, Naomi, and Yvonne can sort some
Library books in 11 hours. Working alone, it would take Yvonne
5 hours and Mark 6 hours to do the same job. How long to the
nearest quarter hour) would it take Naomi, if she worked alone?

Answer 1

Answer:

It will take Naomi 22 hours

Step-by-step explanation:

If they work together Mark, Naomi, and Yvonne take 11 hours, which means

three people represent 3* 11 = 33 man* hours

If they work alone Yvonne will take  5 man hours, and Mark will take 6* man hours.

Now we know that together they take 33 man hours therefore we have

5+ 6+ N = 33

Where N is Naomi's man* hours. We solve for N and get:

N = 33 - 11 = 22

N = 22

Naomi will take 22 hours to finish the job if she worked alone.