Q&A - PSLE Math

[tianzhu]

Chenonceau:

Can someone help? Thanks!


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Hi

Good Morning.

Please refer to a slide for a similar question.

The solution for your question.

The number of blue markers stays the same before and after.

50:25 --- 2:1

First scenario
Red markers ----- 4 units + 500
Blue markers ----- 2 units

Second scenario
Red markers ------- 1 unit + 800
Blue markers ------- 2units

3 units ------ 300
1 unit ----- 100

Red markers ------ 900
Blue markers ------ 200

900+200 ------1100

Best wishes.

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[Chenonceau]

Dear Tianzhu… many thanks. It is clear.

[susutoo]

Please help these two Q:

1) the ratio of the sum, the different and the product f two whole number is 5:1:24. find the bigger number.

2) Tom bought some marker and files in the ratio 4:3. If the ratio of the total amount spent on markers to that of files was 2:1, find the ratio of the cost of marker to the cost of a file. :?

[susutoo]

Can someone help to solve this problem:


80% of the children in the hall are girls. After 48 girls and 2 boys left the hall, the rest of the children are group into groups of 9 children. In each group there were 2 boys. Find the number of children in the hall at first.

[Bunny27]

susutoo:

Can someone help to solve this problem:


80% of the children in the hall are girls. After 48 girls and 2 boys left the hall, the rest of the children are group into groups of 9 children. In each group there were 2 boys. Find the number of children in the hall at first.

Hi, someone pls help:
Abit confused..

A box contained some $1 coins and 50¢ coins in the ratio 2 : 3. Sean took out three $1 coins and exchanged for 50¢ coins. The money was then put back in the box and the ratio became 1 : 3. What is the sum of money in the box??

Thanks

[tianzhu]

susutoo:

Can someone help to solve this problem:


80% of the children in the hall are girls. After 48 girls and 2 boys left the hall, the rest of the children are group into groups of 9 children. In each group there were 2 boys. Find the number of children in the hall at first.

Hi

You may use \"Units and Parts\"

At first
Boys:Girls ----- 1unit (20%) :4 units (80%)

Change
Boys:Girls ----- -2: -48

In the end
Boys:Girls ----- 2 parts:7 parts

Equalise the parts or cross multiply.

1 unit - 2----- 2 parts
(x7)
7 units – 14 ------ 14 parts

4 units – 48 ------ 7 parts
(x2)
8 units – 96 ------ 14 parts

7 units – 14 ------ 8 units – 96
1 unit ------ 82

Number of children in the hall at first ------ 5*82 ------ 410

Best wishes

[susutoo]

Thanks!!

[tianzhu]

Bunny27:

A box contained some $1 coins and 50¢ coins in the ratio 2 : 3. Sean took out three $1 coins and exchanged for 50¢ coins. The money was then put back in the box and the ratio became 1 : 3. What is the sum of money in the box??
Thanks

Hi

You may use \"Units and Parts\"

three $1 coins ----- $3 ------ six 50¢ coins

At first
$1 coins: 50¢ coins ----- 2 units:3 units

Change
$1 coins: 50¢ coins ----- -3 : +6

In the end
$1 coins: 50¢ coins ----- 1 part :3 parts

Equalise the parts or cross multiply.

2 units – 3 ------ 1 part
(x3)
6 units – 9 ----- 3 parts

3 units + 6 ------ 3 parts

6 units – 9 ------ 3 units + 6

3 units ------ 15
1 unit ------ 5

10*1 ------ 10
15*0.5 ------ 7.5

Total ------ 17.50

Best wishes

[susutoo]

Two more Q:

1) the ratio of the sum, the different and the product f two whole number is 5:1:24. find the bigger number.

2) Tom bought some marker and files in the ratio 4:3. If the ratio of the total amount spent on markers to that of files was 2:1, find the ratio of the cost of marker to the cost of a file.

[MathIzzzFun]

susutoo:

Two more Q:

1) the ratio of the sum, the different and the product f two whole number is 5:1:24. find the bigger number.

2) Tom bought some marker and files in the ratio 4:3. If the ratio of the total amount spent on markers to that of files was 2:1, find the ratio of the cost of marker to the cost of a file.

Hi
Q1.

Larger number --> 3u
smaller number --> 2u
ratio of difference : product = 1 : 24 --> 6u = 24, u = 4
Larger number = 12, smaller number = 8

Q2.
cost per unit of markers : cost per unit of files = 2/4 : 1/3 = 1/2 : 1/3

cost of 1 marker : cost of 1 file = 3 : 2

cheers.