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 By: mlteo (offline)  Saturday, September 22 2012 @ 10:47 PM CDT (Read 1492 times)
mlteo

Need help with this question.

Mary had some \$5 and \$10 notes in her wallet. There was a total of 60 pieces of notes at first.
She used half of the number of \$5 notes and received another twelve \$10 nots from her mother.
After that, the number of \$10 notes she had was 2/3 of the remaining number of \$5 notes she
How much money did she have at first ?

Thanks for any help.

Newbie

Registered: 12/31/06
Posts: 10

 By: echeewh (offline)  Sunday, September 23 2012 @ 07:49 AM CDT
echeewh

Hey mlteo,

Following pls find my worked solution:

** - used as buffer for alignment.

<After>
* \$5 |----------|----------|----------|
\$10 |----------|----------|

<Process>
work backwards to develop the <Before> model as follows:
\$5 notes: Doubled
\$10 notes: -12

<Before>
* \$5 |----------|----------|----------|----------|----------|----------|
\$10 |----------|--|<12>

Given Total Qty (notes) <before> is 60, we have ...

8u - 12 --> 60
8u --> 60 + 12 = 72
1u --> 9

At first,
\$5: 6u --> 6 x 9 = 54
Value: 54 x 5 = \$270

\$10: 2u - 12 --> (2 x 9) - 12 = 6
Value: 6 x 10 = \$60

Total value (at first) = 270 + 60 = \$330

========================

Trust this helps.

Do let me know again if there's further clarification.

Cheers,
Edward

Active Member

Registered: 04/21/11
Posts: 627

 By: mlteo (offline)  Monday, September 24 2012 @ 04:22 AM CDT
mlteo

Thanks a lot.

You sure made it look so simple.

Some how they always look simple when explained.

Newbie

Registered: 12/31/06
Posts: 10

 By: echeewh (offline)  Monday, September 24 2012 @ 07:33 PM CDT
echeewh

U re welcome, mlteo.

Actually if you know most of the methods n concepts, I believe one is able to perform better or even excel.

For this question, its only using the basic model concept using <work backwards> method plus the <number x value> method.

Good luck and all the best in your / your child's PSLE.

Cheers,
Edward

Active Member

Registered: 04/21/11
Posts: 627

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