Q&A - PSLE Math

[raysusan]

lizawa:

heutistmeintag:

oh i see, now I can solve by alegbra.


B=20+G

1/3G+1/4B=19
4G+3B=19*12=228
4G+3*(20+G)=228
4G+60+3G=228
7G=228-60
7G=168
G=24
B=20+24=44
Total number of children invited is (24+44)=68

ok, can someone explain using modelling?

Solve by model :
--------------------
Boys : 12u + 20
Girls : 12u

1/4 boys did not come -> 3u + 5 (you can break 20 into 4 parts, each part is 5)
1/3 girls did not come -> 4u

7u + 5 = 19
1u = 2
Altogether -> 24u + 20 = 48+20 = 68.

is this the Q47?

[lizawa]

raysusan:

lizawa:

[quote=\"heutistmeintag\"]oh i see, now I can solve by alegbra.


B=20+G

1/3G+1/4B=19
4G+3B=19*12=228
4G+3*(20+G)=228
4G+60+3G=228
7G=228-60
7G=168
G=24
B=20+24=44
Total number of children invited is (24+44)=68

ok, can someone explain using modelling?

Solve by model :
--------------------
Boys : 12u + 20
Girls : 12u

1/4 boys did not come -> 3u + 5 (you can break 20 into 4 parts, each part is 5)
1/3 girls did not come -> 4u

7u + 5 = 19
1u = 2
Altogether -> 24u + 20 = 48+20 = 68.

is this the Q47?[/quote]Hi raysusan,

I don't think so. Q47 should be a 5-mark question. This doesn't look like a 5-mark question to me.

[kiasuson]

According to my son, Q47 is about speed and the above discussed question is the last question of the paper and it is 5 marks. Anyway, same situation as lizawa… We will not want to probe our son about something that is over and done…They still have another 2 or 3 papers to go…

[Priskhipo]

lizawa:

raysusan:

[quote=\"lizawa\"]
Solve by model :
--------------------
Boys : 12u + 20
Girls : 12u

1/4 boys did not come -> 3u + 5 (you can break 20 into 4 parts, each part is 5)
1/3 girls did not come -> 4u

7u + 5 = 19
1u = 2
Altogether -> 24u + 20 = 48+20 = 68.

is this the Q47?

Hi raysusan,

I don't think so. Q47 should be a 5-mark question. This doesn't look like a 5-mark question to me.[/quote]Hi All,
This question is the last one and it is 4 marks.

[kiasuson]

Those interested to know more on PSLE can read this forum.


http://forum.channelnewsasia.com/viewtopic.php?t=183752

[cutemum]

can anyone help me?


Three girls, Anna, Beatrice and Calista shared a roll of ribbons. Anna’s share was 1/4 of the total length of Beatrice’s and Calista’s ribbon. Beatrice’s share was 2/3 of the total length of Anna’s and Calista’s ribbon. If Anna’s share of ribbons is 45 cm less than beatrice’s share, what is the total length of the roll of ribbons?.

[lizawa]

cutemum:

can anyone help me?


Three girls, Anna, Beatrice and Calista shared a roll of ribbons. Anna's share was 1/4 of the total length of Beatrice's and Calista's ribbon. Beatrice's share was 2/3 of the total length of Anna's and Calista's ribbon. If Anna's share of ribbons is 45 cm less than beatrice's share, what is the total length of the roll of ribbons?.

A : B+C
= 1:4

B: A+C
= 2: 3

Note that the total no. of units in both cases are equal, ie 5 units. So the size of unit in each case is the same.

A: B
= 1:2
Since A has 45cm less than B,
1 unit = 45 cm
5 units = 45 *5 = 225 cm

Total length = 225cm.

[cutemum]

yeah, that’s the answer, thank you so much lizawa…

[caroline3sg]

Lizawa

It seems the bulk of P6 maths is ratio, percentage, fractions (of course whole numbers) using algebra.

Do you know of any good tutor?

[lizawa]

caroline3sg:

Lizawa

It seems the bulk of P6 maths is ratio, percentage, fractions (of course whole numbers) using algebra.

Do you know of any good tutor?

Thank you

Yes, it's an extension of P5 work, with a little more thinking and questions are phrased a little more complex. The trick is not to be restricted to 1 method. Even if the question is phrased with lots of percentage, it could be easier to solve with ratio or fraction. For this, the child has to be able to see the relationship among the topics.

Sorry, I don't know any good Maths tutor. I coach my children myself. I use the Andrew Er Challenging problems book. Based on experience, if your child can complete the problem sums in there with no problems, then, should not have problem for Maths.

BTW, there is going to be a change in the Maths syllabus. Starting next year, PSLE Maths will have 2 papers. 1 with calculator and 1 without calculator.