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Friday, October 20 2017 @ 11:16 AM CDT
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 Nanyang PY Math Prelim Question - please help
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By: iyap (offline)  Friday, September 13 2013 @ 05:45 AM CDT (Read 1247 times)  
iyap

Hi I have the following question (see attachment) that I hope to get help to solve. I know how to solve algebra way but not the heuristic way - woud like to ensure that my girl learns the right way. Thanks.

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By: jo sarah (offline)  Friday, September 13 2013 @ 08:08 AM CDT  
jo sarah

Hi, I am having problem accessing your "attachment", so can't figure which question you need help in. If possible, how about typing the question?

By and large, if your child have no problem handling algebra, there is nothing wrong solving using algebra. A solution that is correct is correct; many questions can be solved using more than one approach.

Let me know how i can help.

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By: echeewh (offline)  Friday, September 13 2013 @ 08:27 PM CDT  
echeewh

Hey <iyap>

Guess u forgot to put in your attachment of the question here . Can you pls put in the attachment of your question or at least indicate the paper and question number and for which year ?? Smile

Thank you ,
Edward

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By: iyap (offline)  Saturday, September 14 2013 @ 02:25 AM CDT  
iyap

apologies...i am a confirmed newbie Oops! first time posting. just realised that the attachment file format is not compatible for upload. here's the test paper - question 16.

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By: echeewh (offline)  Saturday, September 14 2013 @ 06:57 PM CDT  
echeewh

Hi <iyap>

Following is my worked solution:

<Pizzas Recd>

G : B
3 : 1

<Number of Children>

G : B
1 : 1

Given each boy took (2/9)pizza and each girl took (1/6)pizza,

Number of pizzas eaten:
B = 1u × (2/9) = (2/9)u

G = 1u × (1/6) = (1/6)u

Since the boys finished all the pizzas,

(2/9)u = 1p -- (1)

And the girls received 3 times as many as boys,

3p = 3 × (2/9)u = (2/3)u

Pizzas left by girls:
= (2/3)u - (1/6)u = (3/6)u

Given that girls had 4 1/2 pizzas left,
(3/6)u = 4 1/2 = (9/2) pizzas
1u --> (9/2) × (6/3) = 9

Substitute in (1)
1p = (2/9)u = (2/9) × 9 = 2 pizzas

Total number of pizzas:
4p = 4 × 2 = 8 pizzas

=========

Trust this helps.

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

Cheers,
Edward

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By: iyap (offline)  Sunday, September 15 2013 @ 03:29 AM CDT  
iyap

This is really helpful. Thanks Smile

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By: jo sarah (offline)  Monday, September 16 2013 @ 12:57 AM CDT  
jo sarah

Hi, this is my simple solution:

This is a one-variable question.
Since there is an equal no. of girls and boys, we assign the no. of pizzas as follows:

To the girls: 3u
To the boys: 1u
Thus, total no. of pizzas will be 4u.

Now, we find the no. of girls and also no. of boys based on what they eat: each girl ate 1/6 and each boy 2/9 of a pizza.

The no. of girls = (3u - 4.5) / (1/6) = no. of boys = 1u / (2/9)
Therefore,
(3u - 4.5) x (6/1) = 1u x (9/2)
18u - 27 = 4.5u
And, 1u = 2

Therefore, there are 4 x 2 = 8 pizzas. Big Grin

Cheerio!

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