Q&A - PSLE Math

[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.

[kiasuson]

Anymore interesting questions that were feedback from the children? My son said the paper was ok as expected…

[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…