Q&A - PSLE Math

[Chan09]

Need some help, please


1) A,B, C received some sweets. A received 1/11 of the sweets. B received 1/4 of the number of sweets C received. When C gave away 104 sweets to be shared between A and B, they found all of them had the same number of sweets. How many sweets were there at first?

2) x and Y shared the cost of dinner in the ratio 2:3. X used half of his money to pay for his share. After paying for her share, Y had $84 left. The ratio of the amt of money X had at first to the amt of money Y had at first was 3:4. How much was the total bill for the dinner.

Thank you in advance.

[corneyAmber]

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[corneyAmber]

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[small]

Need some advice and thanks in advance.


Question:
There are 42 pupils in each of the classes, Primary 5A and Primary 5B. The ratio of the number of boys in Primary 5A to the number of boys in Primary 5B was 3:4. The ratio of the number of girls in Primary 5A to the number of girls in Primary 5B was 4:3. There were 56 boys altogether in both classes.
What was the ratio of boys in Primary 5A to the number of girls in Primary 5B?
(Given answer is 1:1 but my DS’s answer is 12:5)

[bobsg01]

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Answer given was $655

But have problem how it was derived.

Hope after today, the MOE will do some self reflection on S'pore PSLE math. It's really tough for our young child.

[MathIzzzFun]

small:

Need some advice and thanks in advance.


Question:
There are 42 pupils in each of the classes, Primary 5A and Primary 5B. The ratio of the number of boys in Primary 5A to the number of boys in Primary 5B was 3:4. The ratio of the number of girls in Primary 5A to the number of girls in Primary 5B was 4:3. There were 56 boys altogether in both classes.
What was the ratio of boys in Primary 5A to the number of girls in Primary 5B?
(Given answer is 1:1 but my DS’s answer is 12:5)

Hi small,

The question is ambiguous - 2 possible answers.

1)
5A = B B B G G G G = 42
5B = B B B B G G G = 42
Total 7B + 7G = 84, B+G= 84/7 = 12

From 5A = B B B G G G G = 42 => G =6
5B = B B B B G G G = 42 => B = 6
So, G = B = 6

Ratio of 5A boys to 5B girls = 1: 1

2)
5A = B B B G G G G = 42
5B = B B B B G G G = 42
Total 7B + 7G = 84, B+G= 84/7 = 12

Given total number of boys = 56
so 7B = 56, B =8, G=4

5A boys : 5B girls = 3 x 8 : 3 x 4 = 2 : 1

cheers.

[ozora]

tianzhu:

Hi


For Q1,you may use Systematic Listing by working out a list of equivalent ratios.
You may also use the concept of “Two changed quantities”

In this illustration, I am using UM, basing on the concept that the total value of coins remains the same before and after.

As for Q2, please refer to the underlined sentence, you may wish to check your source again.

Shop A has 164 more customers than shop B . After 1/4 of the customers in shop A and went to shop B, there was 48 more customers in shop A than in shop A. How many customers were there in shop A and shop B respectively?

I think there are are some missing words in this sentence.Also,it should read as “there were 48 more customers in shop A than in shop B”. The question is also a bit vague, does the number of customers refer to the before or after scenarios. I’ve worked out both.

May I take this opportunity to wish all mothers in KSP a very “Happy Mother’s Day”
And to the two very wonderful women in my life, Thank you for all your support.

Best wishes

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thanks for the guide.
sorry for the mistake I made. It is actually \"there were 48 more customers in shop B than in shop A”.

[small]

MathIzzzFun:

small:

Need some advice and thanks in advance.


Question:
There are 42 pupils in each of the classes, Primary 5A and Primary 5B. The ratio of the number of boys in Primary 5A to the number of boys in Primary 5B was 3:4. The ratio of the number of girls in Primary 5A to the number of girls in Primary 5B was 4:3. There were 56 boys altogether in both classes.
What was the ratio of boys in Primary 5A to the number of girls in Primary 5B?
(Given answer is 1:1 but my DS’s answer is 12:5)

Hi small,

The question is ambiguous - 2 possible answers.

1)
5A = B B B G G G G = 42
5B = B B B B G G G = 42
Total 7B + 7G = 84, B+G= 84/7 = 12

From 5A = B B B G G G G = 42 => G =6
5B = B B B B G G G = 42 => B = 6
So, G = B = 6

Ratio of 5A boys to 5B girls = 1: 1

2)
5A = B B B G G G G = 42
5B = B B B B G G G = 42
Total 7B + 7G = 84, B+G= 84/7 = 12

Given total number of boys = 56
so 7B = 56, B =8, G=4

5A boys : 5B girls = 3 x 8 : 3 x 4 = 2 : 1

cheers.

Hi MathIzzzFun,

Many thanks for your time.

[MathIzzzFun]

small:

MathIzzzFun:

[quote=\"small\"]Need some advice and thanks in advance.


Question:
There are 42 pupils in each of the classes, Primary 5A and Primary 5B. The ratio of the number of boys in Primary 5A to the number of boys in Primary 5B was 3:4. The ratio of the number of girls in Primary 5A to the number of girls in Primary 5B was 4:3. There were 56 boys altogether in both classes.
What was the ratio of boys in Primary 5A to the number of girls in Primary 5B?
(Given answer is 1:1 but my DS’s answer is 12:5)

Hi small,

The question is ambiguous - 2 possible answers.

1)
5A = B B B G G G G = 42
5B = B B B B G G G = 42
Total 7B + 7G = 84, B+G= 84/7 = 12

From 5A = B B B G G G G = 42 => G =6
5B = B B B B G G G = 42 => B = 6
So, G = B = 6

Ratio of 5A boys to 5B girls = 1: 1

2)
5A = B B B G G G G = 42
5B = B B B B G G G = 42
Total 7B + 7G = 84, B+G= 84/7 = 12

Given total number of boys = 56
so 7B = 56, B =8, G=4

5A boys : 5B girls = 3 x 8 : 3 x 4 = 2 : 1

cheers.

Hi MathIzzzFun,

Many thanks for your time. :)[/quote]Hi small,

you are welcome :lol:

cheers.

[MathIzzzFun]

small:

MathIzzzFun:

[quote=\"small\"]Need some advice and thanks in advance.


Question:
There are 42 pupils in each of the classes, Primary 5A and Primary 5B. The ratio of the number of boys in Primary 5A to the number of boys in Primary 5B was 3:4. The ratio of the number of girls in Primary 5A to the number of girls in Primary 5B was 4:3. There were 56 boys altogether in both classes.
What was the ratio of boys in Primary 5A to the number of girls in Primary 5B?
(Given answer is 1:1 but my DS’s answer is 12:5)

Hi small,

The question is ambiguous - 2 possible answers.

1)
5A = B B B G G G G = 42
5B = B B B B G G G = 42
Total 7B + 7G = 84, B+G= 84/7 = 12

From 5A = B B B G G G G = 42 => G =6
5B = B B B B G G G = 42 => B = 6
So, G = B = 6

Ratio of 5A boys to 5B girls = 1: 1

2)
5A = B B B G G G G = 42
5B = B B B B G G G = 42
Total 7B + 7G = 84, B+G= 84/7 = 12

Given total number of boys = 56
so 7B = 56, B =8, G=4

5A boys : 5B girls = 3 x 8 : 3 x 4 = 2 : 1

cheers.

Hi MathIzzzFun,

Many thanks for your time. :)[/quote]Hi small,

you are welcome :lol:

cheers.