Q&A - PSLE Math

[KSP]

Hi Winx5015,


1a. 11, b. 31
2. 960

Is the ans correct?

[bbkoala]

Hi


Need help on the following question:

Mrs Tay bought 72 plastic and wooden hangers. Each plastic hanger costs $1.50 and each wooden hanger costs $3.50. She spent $42 more on wooden hangers than plastic hangers. How many wooden hangers did she buy?

DD’s teacher’s answer is 30.
The steps as follows:
$42/3.50=12, 72-12=60, 60/2=30.

Need help to understand why these steps are taken.

[tianzhu]

Winx5015:

Hi,


Below are 2011 PSLE math questions, can anyone help to solve?

(1) Nurul and Peili went shopping together with a total sum of $60. Nurul spent twice as much as Peili. the amount Peili had left was $7 more than what she had spent. She had twice as much money left as Nurul.
(a) How much money did Peili spend?
(b) How much money did Nurul have at first?

Hi

For Q1,you may use MD.

Start with the “after” MD.

In the end (money left)
Peili ------ 2 units (boxes) + 7
Nurul ------ 1 unit + 3.5

Now work backwards

In the beginning
Peili ------- 2 units + 2 units + 7
Nurul ------- 4units + 1 unit + 3.5

5 units + 7 + 3.5 ------ 60
5 units ------ 49.5
1 unit ------ 5.5

Peili spent ------- (2*5.5) ------- 11

Nurul -------- (5*5.5) + 3.5 ------ 31

Best wishes

[tianzhu]

Winx5015:

Hi,

(2) Mrs Hoon made some cookies to sell. 3/4 of them were chocolate cookies and the rest were almond cookies. After selling 210 almond cookies and 5/6 of the chocolate cookies, she had 1/5 of the cookies left. How many cookies did Mrs Hoon sell?

Hi

For Q2, you may use UM or MD.

I’ll give you some pointers.

Use 40 units.

Chocolate cookies (sold) -------- 25 units (5/6 of 30 units)

Chocolate cookies left ------- 5 units

1/5 of cookies left ------- 1/5*40 -------8 units

Almond cookies left ------- 8-5 ------ 3 units

Almond cookies sold ------ 10-3 ------ 7 units

Almond cookies sold ------- 210

7 units ------ 210
1 unit ------- 30

32*30 ------- 960(number of cookies sold)

Best wishes

[happyheart]

Dear Tianzhu,

Thanks again for your kind words and advice. In fact, my DS is still in P5. Sorry to have misled you. When I mentioned history, Geography etc, he so happen to be so interested in those subjects that he will reach out on his own to look for books, articles for those information and he remember the info after reading them. It just that for Maths, he can do many sums but still forget how to go about it.

I agree with you. He needs to understand the concept rather than just remembering the formulas. Thanks again for your encouragement. I will try to fine tune the way he approaches Maths.

Have a good day!

[tianzhu]

bbkoala:

Hi


Need help on the following question:

Mrs Tay bought 72 plastic and wooden hangers. Each plastic hanger costs $1.50 and each wooden hanger costs $3.50. She spent $42 more on wooden hangers than plastic hangers. How many wooden hangers did she buy?

DD's teacher's answer is 30.
The steps as follows:
$42/3.50=12, 72-12=60, 60/2=30.

Need help to understand why these steps are taken.

Hi

The answer is correct, but I am still trying to understand the teacher’s logic and steps.

This is a typical question on “Make a Supposition” type of questions.

Maybe, you can try this question. I’ve changed some numbers.

Mrs Tay bought 72 plastic and wooden hangers. Each plastic hanger costs $3 and each wooden hanger costs $5. She spent $24 more on wooden hangers than plastic hangers. How many wooden hangers did she buy?

Best wishes

[Bunny27]

MathIzzzFun:

Bunny27:

I'm not sure about tis question......

Colin and Karin save $2378.1/6 of Colin's savings is $41 more than 1/7 of Karin's savings. Find the ratio of Colins savings to Karin's savings. Express your answer in the simplest form.

TIA

Hi

Karin's savings --> 7 units
Colins savings --> 6 x ( 1 unit + 41) = 6 units + 246

total --> 13 units + 246 = 2378
1 unit --> 164

Colin's savings : Karin's savings
= 6 x 164 + 246 : 7 x 164
= 15 : 14

cheers.[/quot



Thank you

[bbkoala]

Hi Tianzhu


Thanks for your reply.
I managed to get the answer 30 using supposition, after reading your message.

Just can't understand the teacher's logic.
And DD insist it's the correct way (bcos teacher says so) but she can't explain why it's done this way.
This is what's worrying me

[fightingmom]

Hi All,

Please help :stompfeet: :stompfeet:

Jim bought some chocolates and gave half of them to Ken. Ken bought some sweets and gave half of them to Jim.

Jim ate 12 sweets and Ken ate 18 Chocolates. After that, the number of sweets and chocolates Jim had were in the ratio 1:7 and the number of sweets and chocolates Ken had were in the ratio 1:4.

How many sweets did Ken buy?

thanks !!!

[fightingmom]

Hi All,


Please help with the following question:

Jim bought some chocolates and gave half of them to Ken. Ken bought some sweets and gave half of them to Jim.

Jim ate 12 sweets and Ken ate 18 Chocolates. After that, the number of sweets and chocolates Jim had were in the ratio 1:7 and the number of sweets and chocolates Ken had were in the ratio 1:4.

How many sweets did Ken buy?

thanks !!!