Q&A - P3 Math

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ChiefKiasu
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Q&A - P3 Math

Post by ChiefKiasu » Wed Apr 16, 2008 10:44 pm

Moderator's Note: Please use this thread to ask for help on specific questions. Please refrain from out of topic chatter in this thread to make it easier for the community to find the answers they need.

From Ai Tong Pri 3 SA1 Maths:

A teacher gave her students some balloons. If she gave 6 balloons to each student, she will have 2 balloons left. If she gave 8 balloons to each student, she will be short of 2 balloons. What is the smallest possible number of students she has?

Try to do this without using ALGEBRA!
Last edited by ChiefKiasu on Fri Aug 21, 2009 7:49 am, edited 4 times in total.

jedamum
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Re: Try to do this question WITHOUT algebra

Post by jedamum » Wed Apr 16, 2008 11:05 pm

ChiefKiasu wrote:From Ai Tong Pri 3 SA1 Maths:

A teacher gave her students some balloons. If she gave 6 balloons to each student, she will have 2 balloons left. If she gave 8 balloons to each student, she will be short of 2 balloons. What is the smallest possible number of students she has?
I'll probably use trial and error method and hope that she is not giving out >100 balloons. :lol:
Ans: 2 students...correct?

ChiefKiasu
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Re: Try to do this question WITHOUT algebra

Post by ChiefKiasu » Thu Apr 17, 2008 7:31 am

jedamum wrote: I'll probably use trial and error method and hope that she is not giving out >100 balloons. :lol:
Ans: 2 students...correct?
That's what we will get when we use algebra, ie. solve for:
6x + 2 = 8x - 2
=> 2x = 4
=> x = 2

Just that the case in question is given the answer of 14 in "illegal" black-market exam papers. Shows how bad the answers can be! So don't trust the answers provided.

Also, it is difficult with people not trained to do modelling to work out this problem without algebra.

jedamum
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Re: Try to do this question WITHOUT algebra

Post by jedamum » Thu Apr 17, 2008 10:00 am

ChiefKiasu wrote:
jedamum wrote: I'll probably use trial and error method and hope that she is not giving out >100 balloons. :lol:
Ans: 2 students...correct?
That's what we will get when we use algebra, ie. solve for:
6x + 2 = 8x - 2
=> 2x = 4
=> x = 2

Just that the case in question is given the answer of 14 in "illegal" black-market exam papers. Shows how bad the answers can be! So don't trust the answers provided.

Also, it is difficult with people not trained to do modelling to work out this problem without algebra.
illegal black-market exams papers aside, nowadays assessment books in the market also have typo, questions and answers error!

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Post by lizawa » Tue Apr 22, 2008 11:38 am

For P3, I expect this question to test on multiplication / division + process skills.

Multiples of 6 : 6, 12, 18,24, ...
+2 (since 2 balloons left) : 8, 14, 20, 26...

Multiples of 8 : 8, 16, 24, 32, ...
-2 (short of 2 ballons) : 6, 14, 22, 30....

Since asking for smallest number of students, the number that match in both cases is 14, hence, number of students is 2.

Liz


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Post by ChiefKiasu » Tue Apr 22, 2008 1:18 pm

lizawa wrote:For P3, I expect this question to test on multiplication / division + process skills.

Multiples of 6 : 6, 12, 18,24, ...
+2 (since 2 balloons left) : 8, 14, 20, 26...

Multiples of 8 : 8, 16, 24, 32, ...
-2 (short of 2 ballons) : 6, 14, 22, 30....

Since asking for smallest number of students, the number that match in both cases is 14, hence, number of students is 2.

Liz
OK... Liz is the one with the right answer and methodology. All of us are "old school". Back to school, everyone.

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Post by lizawa » Tue Apr 22, 2008 1:37 pm

Yeah, when you have to coach your own children from P1 - P6 with all the new-aged methods and syllabus, the only way is to unlearn and relearn. :)

Liz

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Post by phantom » Wed Apr 23, 2008 10:56 am

Talking about unlearn, where can I get information on those new methods?

lizawa
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Post by lizawa » Wed Apr 23, 2008 11:00 am

I follow through my children's text books and look at some of the guide books. Take a while to get used to. The modelling method that they use for Primary Mathematics is very visual. So your child needs to be able to visualize in order to draw the model and solve the problem. It's just another way of solving problems.

Liz

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Post by phantom » Wed Apr 23, 2008 11:03 am

lizawa wrote:I follow through my children's text books and look at some of the guide books. Take a while to get used to. The modelling method that they use for Primary Mathematics is very visual. So your child needs to be able to visualize in order to draw the model and solve the problem. It's just another way of solving problems.

Liz
Wow, looks like a lot of right brain training here. I will start looking at my niece textbook to prepare myself. Thanks for the info!

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