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 By: keenlearner (offline)  Saturday, November 17 2012 @ 08:08 AM CST (Read 1659 times)
keenlearner

Thanks for your help everyone, I seem to always get very confused with the long questions and I can't understand the answer sheet :-(

Mandy had some money. After spending \$31 on 5 notebooks and 8 files, she was short of \$0.40 if she were to buy another notebook. However, she would have \$0.60 left if she were to buy one more file.

a) How much did a notebook cost?
b) How much money did Mandy have?

Junior

Registered: 11/08/12
Posts: 22

 By: echeewh (offline)  Sunday, November 18 2012 @ 03:50 PM CST
echeewh

Hey keenlearner,

Pls refer to "Pls help with maths qs" - Jun 3, 2012.

FYI, if you want to make any reference to SA1 2011 questions etc, kindly do a search of the postings here around the apr, may, jun period , where a number of these questions may have already been answered.

Thank you,
Edward.

Active Member

Registered: 04/21/11
Posts: 627

 By: keenlearner (offline)  Tuesday, November 20 2012 @ 07:08 AM CST
keenlearner

Hi Edward,

Thanks for the solution (I have copied and paste below) and letting me know that these questions have been answered - will search through before posting next time :-)
Some of these problem sums really got me fried, can I get some tip how to make a P5 kid understand simultaneous equations? Or is there a different way to solving this question? Thanks!

Solutions by Edward:

Note: **** - fillup/buffer whitespace for alignment purpose ( i.e. imagine *** as whitespace )

*****31.00 1N
<------------><----------------->
|---------------------------|<--->|
*************************0.40

|---------------------------|
<------------><---><--->
**31.00******1F 0.60

Applying Gap & Difference method, we have ...

1N - 1F = 1.00 --- (1)
5N + 8F = 31.00 --- (2)

As question is interested in N, we shall eliminate F in the following manner:

(1)x8: 8N - 8F = 8.00 ---(3)

Comparing (3) and (2),
(2) + (3):
5N + 8F + 8N - 8F = 31.00 + 8.00
13N = 39
1N = 39 ÷ 13 = \$3

(b)

Amt of money M had = 31 + 1N - 0.40
= 31 + 3 - 0.40 = \$33.60

Junior

Registered: 11/08/12
Posts: 22

 By: echeewh (offline)  Friday, December 14 2012 @ 06:27 PM CST
echeewh

hey there,

Responding to your comment - very confused with the long questions , perhaps you would like to try the following:

Break long sentences into shorter but logical ones;
Transform each sentence into mathematical expressions / statements that one understands;

Your Q - can I get some tip how to make a P5 kid understand simultaneous equations?

if you remember, one was taught how to solve mathematical problems with symbols / objects representing numbers in P2, P3 and probably P4. That forms the basis of problem-solving skills leading to what is known as simultaneous equation in upp primary, secondary sch and beyond. As far as skills and methods are concerned, one should not limit yourself. Learn the method gradually and you will find it useful in solving problems.

Are you not able to follow my worked solution step-by-step?

------------------

Referring to my worked solution for this Q, here's another way of looking at it.

(a)

Using the same model (which I believe you can understand),

1F = 1N - 1.00 { A File cost \$1 less than a Notebook }
5N and 8F were bought for \$31.

8F = 8 × ( 1N - 1.00 ) = 8N - 8.00
5N + 8N - 8 = 31
13N = 39
1N = 3

hence, one notebook cost \$3

(b) follows the solution as per provided.

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

Cheers,
Edward

Active Member

Registered: 04/21/11
Posts: 627

 By: keenlearner (offline)  Thursday, December 20 2012 @ 02:27 PM CST
keenlearner

Hi Edward, thank you so much for taking time to clarify my doubts. You are a star!! :-)

Junior

Registered: 11/08/12
Posts: 22

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