Q&A - PSLE Math

[tianzhu]

zsqchx:

Hi Tianzhu,Thank you very much!

Hi

You're welcome.

Best wishes

[match3frog]

Hi, please help with this 2 questions.


Q1: Ms Siti bought sweets just enough to distribute to the class. Each pupil receive 10 sweets. However, when 15 more pupils joined the class, each pupil could only receive 7 sweets with 60 sweets remaining. How many pupils were in the class at first?

This is my workings:

15 x 7 + 60 = 165
10 - 7 = 3
165 / 3 = 55

Q2: A packet of cookies was shared equally among 9 children. If 4 more children joined in, each child would get 8 fewer cookies. How many cookies were there in the packet?

My workings:
9+4 = 13
13 x 8 = 104
104/4 = 26
26x9 = 234

Are my methods correct? How do I explain the solution in a way to make my child understand? Are there alternative methods to these questions?

Thank you for your time!

[tianzhu]

match3frog:

Are there alternative methods to these questions?

Hi

Good Morning.

Perhaps a more direct way for Q2 would be

8*9 ------72
72 cookies are given to 4 children.

Each children receives 72/4 or 18 cookies

13*18 ------234

Best wishes

[kavisuresh]

Hi Tianzhu, I have given link to papers, as you suggested.


Pls help to give solutions to problems 10, 11, 17, 18 of paper 2 .
http://orlesson.com/10Ma/2010-P6-Math-SA2-Rosyth.pdf

please help in solving questions 3,4,6,16,17,18 of paper 2.
http://orlesson.com/10Ma/2010-P6-Math-SA2-Nanyang.pdf

Please help in solving questions 8,11,15,16 of paper 2.
http://orlesson.com/10Ma/2010-P6-Math-SA2-MGS.pdf

Please help in solving questions 5,7,10,11,14,15,16,17,18 of paper 2.
http://orlesson.com/10Ma/2010-P6-Math-SA2-CHS.pdf
Thanks a ton.

[tianzhu]

Hi


Circle P6 2010 SA2 Nanyang P2 Q18
This question was discussed in one of the earlier posts.

Q18 looks intimidating at first glance. It helps if one can rearrange the shaded areas.

What I am sharing here may help students who prefer to work with more familiar shapes. It may not be the shortest way.

Interestingly, the rearranged figure looks like a big eye and a small eye.

PSLE students should be familiar with calculating the areas of shaded area within the 3cm square (big eye) and the small eye within the 1cm square.

The area of the shaded area in Q18 is the 2(area of big eye – area of small eye)

Best wishes

http://farm5.static.flickr.com/4085/4988720284_36afd045ba_z.jpg\">

[tianzhu]

Rosyth P6 Prelim 2010 P2: Q18: Xavier, Yati and Zul each had a certain number of stamps. At first, Yati had 200 stamps more than Xavier and Zul had ¾ the number of stamps Yati had. After Yati gave away 1/8 of her stamps to Xavier, she had 60 fewer stamps than Xavier. What was the ratio of the number of stamps Xavier had to the number of stamps Yati had to the number of stamps Zul had at first? Give your answer in the simplest form. [5 marks][Answer given: 42:52:39]


Hi

Hope this helps.

You may wish to draw a MD.

At First
X ------8units
Y ------- 8 units+200
Z -------3/4 of Y

In the End
X -------9 units + 25
Y ------7 units + 175
Z remains the same

7units+175+60 ----- 9 units +25
1 unit ------105

X ------- 105*8 ------ 840
Y -------1040
Z -------780 (3/4 of Y)


Therefore X:Y:Z ---------- 42:52:39

Best wishes

[match3frog]

Thank you, tianzhu. Yes, your workings are much easier to understand

[tianzhu]

Hi


I am sorry; I don’t have the time to do MD or detailed presentation, just rushing to give you some pointers.

Rosyth P2 Q 11 2010

It’s important to note that the total number of units remains the same.

A: (B+C) ----- 1 :3 -------4 (total)
B: (A+C) ----- 1:5 ------- 6 (total)

Use equivalent ratios,
A: (B+C) ----- 3 :9 -------12 (total)
B: (A+C) ----- 2:10 ------- 12 (total)

A ----- 3 units
B ------2 units

B+C ---- 9
A+C ---10
Therefore C ------7 units

7 units – 2 units ------50
1 unit ----- 10
12 units -----120(cost of present)


Rosyth P2 Q 17 2010

Original time from KL to Singapore ----- 6.5h

Consider the second half of journey

Time ------- 4: 4.5 ------- 8:9
Speed -------9:8

1 unit -----8.5km/h
8 units ------ 68 km/h

Distance between Kuala Lumpur and Singapore ------68*6.5 ----- 442km

Rosyth P2 Q 10 2010

It is helpful to draw a simple diagram.

Usha ------- 3 units
George ------ 2 units
Cecelia ------ 3 units -100.

From diagram, you’ll see that 2 units ------ 350 -100 ----- 250

Hence 1 unit -----125

Cecilia ------ (3*125) – 100 -----275

Best wishes

[tianzhu]

match3frog:

Thank you, tianzhu. Yes, your workings are much easier to understand

Hi

You’re welcome.

Enjoy the maths journey with your kid.

Best journey.

[tianzhu]

Hi


NY SA2 Q16 2010

Each boy ate 2/9 of a pizza and each girl ate 1/6 of a pizza
Use a common multiple of 18

Boys ----- 4 units
Girls ----- 3 units

The girls received thrice as many pizzas as the boys.

Boys ----- 4 units
Girls ----- 12 units

12 – 3 ----- 9

9 units -----4.5 pizzas

16 units ----- 8 pizzas

Best wishes