word problem

Question

In 66 ?hours, an experienced cook prepares enough pies to supply a local? restaurant's daily order. Another cook prepares the same number of pies in 77 hours. Together with a third? cook, they prepare the pies in 22 hours. Find how long it takes the third cook to prepare the pies alone.

Answer 1

Mark is right on, except for a small math error.  22/66 is actually 1/3 of the job, not 2/3.  If you correct that, the time for the third baker to complete the entire job alone drops from an abysmal 462 hours, to a more competitive 57.75 hours.

Answer 2

In 22 hours experience cook does 22/66 or 2/3 of the job.

In 22 hours "another" cook does 22/77 or 2/7 of the job

Together they complete 20/21 of the job. (2/3 + 2/7) use LCD 21)

 

The third cook takes 22 hours to do 1/21 of the job.

Working alone the third cook would need 462 hours (21 times 22) Not much help!