Q&A - PSLE Math

[tianzhu]

vidhyalog:

Thanks Tianzhu. Could I find out though - why is it that the bigger square would have an area that is 2X the area of the smaller square? Pardon my ignorance ..... would like to work it out myself, but in the interest of time - taking short cut of asking you.
Thanks in advance

Hi vidhyalog

I'll prepare the slide and post it tomorrow.

Best wishes

[Vanilla Cake]

Hi,

As per request from some KSP members, these are some of the questions from this paper. Answers given have not been checked and pls share your way of solving them. TIA.

Q15
A rectangular tank measuring 3 m by 3 m by 1.5 m was 1/3 filled with water. A tap was turned on to fill up with water at a rate of 18 l/min. Every 2 minutes after the tap was turned on, 6 l of water was poured from a pail into the tank. How long did it take for the rectangular tank to be completely filled with water? Leave your answer as a mixed number in its simplest form. [ 4 marks]
Answer given: 428 2/3 min

Q16
In a confectionery, 3/10 of the cupcakes baked were strawberry cupcakes, 1/2 of them were chocolate cupcakes and the rest were grape cupcakes. 2/7 of the strawberry cupcakes were sold. This was 1/2 of the number of chocolate cupcakes sold. The number of grape cupcakes sold was 1/4 the total number sold in the other two flavours. Given that there were 190 cupcakes left, how many cupcakes were there at first? [5 marks]
Answer given: 280

Q17
Packet A, Packet B and Packet C each contained some salt. At first, there were 200 g more salt in Packet A than Packet B. Packet C had 3/4 of the amount of salt in Packet A. After 1/8 of the amount of salt in Packet A was transferred to Packet B, there was 82.15 g of salt in Packet B. How many percent less salt were there in Packet C than Packet A at first? [5 marks]
Answer given: 25%

Q18
In a cinema, the ratio of the number of girls to the number of boys was 3:2. The ratio of the number of women to the number of boys was 5:4. The ratio of the number of girls to the number of men was 2:5. During the movie, 6 women and 27 men left the cinema. The ratio of the number of women to the number of men then became 1:2.
(a) Express the number of women as a fraction of the number of men at first. Leave your answer in its simplest form.
(b) How many children were there in the cinema?
Answer given: (a) 1/3 and (b) 30

[Vanilla Cake]

Q8 and answer given: 75 cm2

http://i52.tinypic.com/2h4xbeo.png\">

[Vanilla Cake]

Unable to load diagrams for Q11 [4 marks] and Q14 [4 marks] as the system says: \" Error 503 Service Unavailable\".

Will ask my mum to post them later.
Thks.

PS: Q1 [2 marks] and Q10 [3 marks] can be found http://www.onsponge.com/forum/35-thinkingmath/14152-p6-nanyang-prelims-2011-qs-1-8-a-10.html.

[Vanilla Cake]

Q11 and answer given : 54720 cm2

http://i51.tinypic.com/34s2yw4.png\">

posted by VC's mum

[Vanilla Cake]

http://i55.tinypic.com/suzriw.png\">


Solution given by supplier:

14)a)28+8=36
36+9=45
45+10=55

b)100÷2=50
99x50=4950
4950+1=4951

Posted by VC's mum

[tianzhu]

Hi VC’s mum


For Q14,the answers you gave are for (b) and .

The answer for (a) -------- 16,17,18,19,20,21.

For part (b) the answer is 55

For part , the answer is 4951.

Best wishes

[MathIzzzFun]

Vanilla Cake:

http://i55.tinypic.com/suzriw.png\">


Solution given by supplier:

14)a)28+8=36
36+9=45
45+10=55

b)100÷2=50
99x50=4950
4950+1=4951

Posted by VC's mum

Hi

... the workings..

http://i54.tinypic.com/2udwaya.jpg\">

cheers.

[tianzhu]

Vanilla Cake:

Q8 and answer given: 72 cm2

Hi

I made a guess on the locations of E, F and G as they are covered in dark shades.

I did a quick check and got an answer of 75.

Best wishes

[Vanilla Cake]

Vanilla Cake:

Q8 and answer given: 72 cm2

tianzhu:

In made a guess on the locations of E, F and G as they are covered in dark shades.
I did a quick check and got an answer of 75.

Hi tianzhu,
Thks for pointing out and your answer is correct. The question itself is not clear and you have to strain your eye to look for the locations of E, F and G in the paper.Sorry that VC had made a typo error as she had to rush to go to school, this morning. Here's the solution by the supplier:

ΔBCD = 1/2
ΔBDH = 1/2 x 1/4 = 1/8
ΔAGB = 1/4
ΔAGF = 1/4x1/3 = 1/12
ΔAGD = 1/4
ΔDGE = 1/4x1/2= 1/8
1/8+1/12+1/8= 1/3
1/3x15x15 = 75 cm2

VC's mum