Math Help

[reddixie]

Ok as ya'll know I am going back to college and am preparing by brushing up on my math etc. Well I keep getting this problem or some variation on websites as I try to brush up.

John can file 20 pages in 30 min. Sue can file the same 20 pages in 15 min. and Jill can file the 20 pages in 10 min. If all three work together how long will it take them to file these 20 pages?

Well I don't even know where to begin. Can anyone help? Thanks

 

[Aurora63]

Good luck!

No, maybe I can help a little...what you need to figure out first is how many pages each can file in 1 minute. I think you figure that out by dividing the number of pages by the time it takes to file them(for instance, John does 20 pages in 30 minutes...20/30=.66 pages a minute.)

John - .66 pages a minute
Sue - 1.33 pages a minute
Jill - 2 pages a minute

After that, I don't know.

 

[Aurora63]

Hi again! I think the answer is five minutes.

Jill files 2 pages a minute...in five minutes, she files 10 pages.

10 pages are left...in that same five minutes, Sue and John can file 2 pages a minute (because John's .66 a minute plus Sue's 1.33 a minute = 2)...2 x 5 is 10, 10+10=20.

I'm almost certain the answer is 5 minutes. Can someone out there check my math?

 

[AnaheimGirl]

Yup, 5 minutes. If you add up all the "pages per minute" in Aurora's first post, it's 4 pages per minute working together. 4 x 5 = 20.

 

[RachelEllen]

YOur math looks right. The general approach is what you stated in the first reply.

1) Figure out how many pages everyone can file in 1 minute.

2) Add those numbers up to figure out how many pages the group can file in 1 minute.

3) Divide the total number of pages needing to be filed by the number you got in 2, to figure out how long it will take the group to file those pages.


hth

 

[challada]

Well, obviously John is filing impaired as it takes him THREE TIMES as long to file the same darn pages. Does he not know his alphabet or something?

So really, you need to get John OUT OF THE WAY for the others to file. Since it seems that John might be a little SLOW in understanding the "just get out of my way" idea, it's going to take one of the two ladies to slow down and talk to him. I suggest Sue since she's the next slowest. Which leaves you only Jill filing the papers and it takes her 10 minutes...so it'll take 10 minutes to get them filed. Maybe at the end of 10 minutes, John will understand why he couldn't play too and Sue will need a drink by then from having to deal w/John for 10 minutes!


Or, I'd go w/Aurora's 5 minute answer.

 

[Simba's Mom]

Yup, I got 5 minutes too. I'm a Math teacher so I was able to pull out an algebra book to check on it.

 

[reddixie]

Thanks so much I wasn't getting anything. I couldn't make heads or tails of how to start much less finish this problem. I now have done 10 similar problems and got the right answer each time. I appreciate all of the help. I did get a great laugh from Challda.

 

[cats mom]

Too funny, I'm with Challada!
What is with that John anyway?
Maybe some restructuring of responsibilities is in order.

I saw this one early on and read it to my girls who both came up with 5 minutes.
But when I asked them how they got the answer they mumbled something about just getting out of school for the summer and not about to work out math problems.

 

[Lisa_Belle]

In the real world, it would take 10 minutes. Because if Jill is efficient and doing all the work, then John will take a smoking break and Sue will be on the phone making lunch plans with her best friend.