Q&A - PSLE Math

[bobsg01]

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Sorry for the messy post as I was having problem with the image upload.

:lovesite:

[tianzhu]

pixiedust:

Appreciate help with this :


In a game, the number of points Mr. Tan had to the number of points Mr. Lim had was 7:4. After Mr. Tan lost 85 points and Mr. Lim gained 85 points, the ration of points Mr. Tan had to that of Mr. Lim became 1:3.

a) how many points did Mr. Tan have at first ?
b) how many more points did Mr. Lim have than Mr. Tan at the end ?

Hi

A quick one .

Mr. Tan lost 85 points and Mr. Lim gained 85 points, so the total points remain the same.

Start ------- Mr Tan: Mr Lim ------- 7:4 --------- (11)
End ------- Mr Tan: Mr Lim ------- 1:3 -------- (4)

Make the total number of units the same.

Start ------- Mr Tan: Mr Lim ------- 7:4 ---------28:16 -------- (44)
End ------- Mr Tan: Mr Lim ------- 1:3 -------- 11:33 ------- (44)

17 units ------ 85
1 unit ------ 5

Mr Tan -------- 28 x 5 ------ 140\t

33 x 5 ------- 165
11 x 5 ------- 55
Mr Lim ------- (165 – 55) ------- 110

Best wishes

[tianzhu]

bobsg01:

http://i55.tinypic.com/2q16qsy.jpg\">

Hi

6 x 2 ------- 12 (6 pupils making 2 bookmarks each)
20 - 12 ------- 8

North is correct, rotate 135 degrees clockwise

Best wishes

[pixiedust]

Thank you tianzhu. I pay you to tutor my son, can ? :lol:

[ozora]

tianzhu:

Hi


In this question, a student should note that the number of apples and oranges remains the same in both scenarios.

A student who is familiar with SE could proceed to use it. If not, he/she could solve it using the alphabet method or pictorially.

In this illustration, I’ve done it pictorially. As usual, I’ve put in more details than necessary because I wanted to show the flow of events. Once you understand the concept, you may express the solution in your own way.

Best wishes.

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thanks for the help/.. it really makes me understand better to assist my nephews .thanks again

[ozora]

sorry need guide about these questions.

a)The number of 20cents coins to $1 coins in Jane’s box is 5:4. She took out 8 $1 coins and exchanged them into 20 cents coins of the same value. The ratio of the number of 20cents coins to $1 coins became 15: 4. What was the amount of money Jane has?
I used equivalent ratio and got $35. I wondered is the answer correct.

Is it possible to use model or units method? If yes, how?

b) Shop A has 164 more customers than shop B . After 1/4 of the customers in shop A and went to shop B, there was 48 more customers in shop A than in shop A. How many customers were there in shop A and shop B respectively?

[tianzhu]

pixiedust:

Thank you tianzhu. I pay you to tutor my son, can ? :lol:

Hi

Good Morning.

You're welcome.

Thank you for having confidence in me.

Best wishes

[tianzhu]

ozora:

thanks for the help/.. it really makes me understand better to assist my nephews .thanks again

Hi

Good Morning.

You're welcome.

Best wishes

[tianzhu]

Hi


For Q1,you may use Systematic Listing by working out a list of equivalent ratios.
You may also use the concept of “Two changed quantities”

In this illustration, I am using UM, basing on the concept that the total value of coins remains the same before and after.

As for Q2, please refer to the underlined sentence, you may wish to check your source again.

Shop A has 164 more customers than shop B . After 1/4 of the customers in shop A and went to shop B, there was 48 more customers in shop A than in shop A. How many customers were there in shop A and shop B respectively?

I think there are are some missing words in this sentence.Also,it should read as “there were 48 more customers in shop A than in shop B”. The question is also a bit vague, does the number of customers refer to the before or after scenarios. I’ve worked out both.

May I take this opportunity to wish all mothers in KSP a very “Happy Mother’s Day”
And to the two very wonderful women in my life, Thank you for all your support.

Best wishes

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[bobsg01]

To: Tianzhu


:thankyou: