Mrs. Crowley has a stack of letters to be typed...........?

If she can type all of the letters in 6 hours and Mr. Crowley can type all of the letters in 9 hours, how long will it take them if they work together?
Mrs. Crowley has a stack of letters to be typed...........?
9 hours.
Mrs. Crowley has a stack of letters to be typed...........?
3.33333333333333333333333333333333333333... hours.
Reply:Tay Tay... you're in minus points and you ask a question about numbers in Books and Authors?


You should be


happy with CJW's answer...





I was going to type '3'... and I will: '3'...





...But going to 3.33333333 to infinity is quite an answer, don't you agree?


3
Reply:Oh, dear. I hate to contradict LJ K, but I think I'll develop a tic in my left eye if I leave that answer uncorrected.





Here's the answer with working:





Mr. Crowley takes half again as long as Mrs. Crowley. That means that if you divide the letters into 5 even stacks, Mrs. Crowley can do 3 stacks in the same time as Mr. Crowley can do 2 stacks.





So: Mrs. does 3 stacks out of 5


Mr. does 2 stacks out of 5





Based on Mrs. Crowley's time of 6 hours, work out how long it would take her to type one stack of letters.


Divide 6 hours into 5 stacks (6 hours/5 stacks = 1.2 hours per stack)


Mrs. does 3 stacks total, so multiply that by the amount of time it takes her to do one.


1.2 hours x 3 stacks = 3.6 hours . It takes Mrs. Crowley 3.6 hours to do her share of the work, and it should take Mr. Crowley the same amount of time.





Proof: Divide the result by 2 stacks for Mr. Crowley.


3.6 hours/2 stacks = 1.8 hours


Then multiply 1.8 hours by the total number of stacks the work was originally broken into. The result of this should show you how long it would take Mr. Crowley to do it on his own.


1.8 hours x 5 stacks = 9 hours.





Solved. Answer is 3.6 hours.