
By: drstevewu (offline) Friday, July 26 2013 @ 10:58 AM CDT (Read 1198 times)



drstevewu 
Hi, I can't make sense of the following question. Need your help.
Question: Harry, Larry and Sean were to share a box of marbles. Harry took 1/5 more than his rightful share of marbles. Larry took 1/3 of the remaining marbles. Sean took his rightful share of marbles. After that, there were 40 marbles left. How many marbles were there in the box at first?
Cheers...

Junior
Registered: 04/20/10 Posts: 27





By: echeewh (offline) Friday, July 26 2013 @ 05:17 PM CDT



echeewh 
Hi <drstevewu>,
My thoughts are that the question may not have been clear enough. I think perhaps one can take it that the box of marbles was shared equally among the 3 boys. Then I believe you can work out the answer easily. And btw, is there any marks given for this question? Or is there an <Answerkey>?. Thank you.
Hope you find this helpful.
Cheers,
Edward

Active Member
Registered: 04/21/11 Posts: 623





By: drstevewu (offline) Saturday, July 27 2013 @ 04:06 AM CDT



drstevewu 
Hi Edward,
Thanks for your reply. I have the answer key but honestly I don't quite agree with it. The answer key is as follow:
"Let there be 30 units of marbles at first, and each boy was to take 10 units.
Harry took 10 + 2 = 12 units, and there were 30  12 = 18 units left.
Larry took 1/3 x 18 units = 6 units, and there were 18  6 = 12 units left.
Sean took his rightful share of 10 units, and there were 12  10 = 2 units left.
2 units = 40 marbles
1 unit = 40/2 = 20 marbles.
At first, there were 30 units, = 30 x 20 = 600 marbles"
I don't agree in that part where it assume there were 30 units at first. I mean how can a student be able to assume there were "30 units" in the first place?
Thank you again for your help.
Cheers,
Steve Wu

Junior
Registered: 04/20/10 Posts: 27





By: echeewh (offline) Saturday, July 27 2013 @ 07:19 PM CDT



echeewh 
Hi Steve,
Yes you have my vote on that too ( with regards to the assumption used / stated in the Answerkey ).
But I believe you do have a more appropriate solution for your child that gives the same result as 600.
Cheers and best regards,
Edward

Active Member
Registered: 04/21/11 Posts: 623



