## Q&A - PSLE Math

### Re: Q&A - PSLE Math

Can anyone help?

There were 180 girls and 150 boys in the Arts Theatre and 210 girls and 560 boys in the School Hall at first. After some boys and girls moved from the School Hall to the Arts Theatre, there were an equal number of boys and girls in the Arts Theatre and thrice as many boys as girls in the School Hall.

How many boys and how many girls were moved from the School Hall to the Arts Theatre?

There were 180 girls and 150 boys in the Arts Theatre and 210 girls and 560 boys in the School Hall at first. After some boys and girls moved from the School Hall to the Arts Theatre, there were an equal number of boys and girls in the Arts Theatre and thrice as many boys as girls in the School Hall.

How many boys and how many girls were moved from the School Hall to the Arts Theatre?

### Re: Q&A - PSLE Math

Girls-->180+210=390Oh Dear wrote:Can anyone help?

There were 180 girls and 150 boys in the Arts Theatre and 210 girls and 560 boys in the School Hall at first. After some boys and girls moved from the School Hall to the Arts Theatre, there were an equal number of boys and girls in the Arts Theatre and thrice as many boys as girls in the School Hall.

How many boys and how many girls were moved from the School Hall to the Arts Theatre?

Boys-->150+560=710

Arts Theatre Boys:Arts Theatre Girls

1u:1u

School Hall Boys:School Hall Girls

3p:1p

1u+3p=710

1u+1p=390

2p=710-390

=320

1p=160

1u=390-160

=230

230-180=50

230-150=80

80+50=130

Ans: 130 boys and girls

### Re: Q&A - PSLE Math

Thank you for your answer. May I ask what is the meaning of (143-128)?NerdyMath wrote:Average difference -- > 146-143=3voltes5 wrote:Appreciate any help on this one...

Jun Kee had some bags of nails. The average number of nails in each bag was 146. After Jun Kee added another bag containing 128 nails, the average number of nails in each bag became 143. How many bags of nails were there after the new bag was added?

143-128 = 15

15/3 = 5

5 + 1 = 6.

Answer:6

Solved by DS.

- alfretztay
- KiasuGrandMaster
**Posts:**1199**Joined:**Sun Sep 12,**Total Likes:**5

### Re: Q&A - PSLE Math

Before :Oh Dear wrote:Can anyone help?

There were 180 girls and 150 boys in the Arts Theatre and 210 girls and 560 boys in the School Hall at first. After some boys and girls moved from the School Hall to the Arts Theatre, there were an equal number of boys and girls in the Arts Theatre and thrice as many boys as girls in the School Hall.

How many boys and how many girls were moved from the School Hall to the Arts Theatre?

Arts Theatre : 180 girls + 150 boys

School Hall : 210 girls + 560 girls

After :

Arts Theatre : 1u girls + 1u boys

School Hall : 1p girls + 3p girls

1u + 1p ------- 180 + 210 = 390

1u + 3p ------- 150 + 560 = 710

2p ------- 320

1p ------- 160

1u ------- 390 - 160 = 230

230 - 150 = 80 (boys moved)

230 - 180 = 50 (girls moved)

Ans : 80 boys and 50 girls.

### Re: Q&A - PSLE Math

alfretztay,alfretztay wrote:I would solve the above problem as follows :NerdyMath wrote:Similar to 2009 PSLE mathematics question.voltes5 wrote:Thanks in advance for the help.

Sally bought some chocolates and gave half of them to Mabel. Sally also bought some lollipops and gave half of them to Mabel. Mabel ate 7 lollipops and Sally ate 16 chocolates.

After that, the number of lollipops and chocolates Mabel had were in the ratio 1:8 and the number of lollipops and chocolates Sally had were in the ratio 1:5. How many lollipops did Sally buy at first?

Answer says 48 but I could not understand how to arrive at it.

Let's start by doing it backwards.

Mabel

L[]

c[][][][][][][][][16]

Sally

L [][7]

C [][7][][7][][7][]7][][7]

Reason why there is an extra 7 is because Sally didnt eat 7 lollipop.

Reason Why there is an extra 16 is because Mabel didn't eat 16 chocolate.

Let's equate.

8u - 16 = 5u + 7x5

8u - 16 = 5u + 35

3u = 35+16

1u = 17

17 + 7 = 24

24X 2= 48

Answer:48

Solved by DS.

For chocolate,

Sally : 2u - 1u - 16 = 1u - 16

Mabel : +1u

For lollipops,

Sally : 2p - 1p = 1p

Mabel : +1p - 7

For Mabel,

(1p - 7) x 8 ------- 1u

8p - 56 ------- 1u

For Sally,

1p x 5 ------- 1u - 16

5p + 16 ------- 1u

8p - 56 ------- 5p + 16

3p ------- 72

1p ------- 72/3 = 24

2p ------- 2 x 24 = 48

Ans : 48 lollipops.

What does this mean?

(1p - 7) x 8 ------- 1u

- alfretztay
- KiasuGrandMaster
**Posts:**1199**Joined:**Sun Sep 12,**Total Likes:**5

### Re: Q&A - PSLE Math

Before :TheSolver wrote:Girls-->180+210=390Oh Dear wrote:Can anyone help?

There were 180 girls and 150 boys in the Arts Theatre and 210 girls and 560 boys in the School Hall at first. After some boys and girls moved from the School Hall to the Arts Theatre, there were an equal number of boys and girls in the Arts Theatre and thrice as many boys as girls in the School Hall.

How many boys and how many girls were moved from the School Hall to the Arts Theatre?

Boys-->150+560=710

Arts Theatre Boys:Arts Theatre Girls

1u:1u

School Hall Boys:School Hall Girls

3p:1p

1u+3p=710

1u+1p=390

2p=710-390

=320

1p=160

1u=390-160

=230

230-180=50

230-150=80

80+50=130

Ans: 130 boys and girls

Arts Theatre : 180 girls + 150 boys

School Hall : 210 girls + 560 girls

After :

Arts Theatre : 1u girls + 1u boys

School Hall : 1p girls + 3p girls

1u + 1p ------- 180 + 210 = 390

1u + 3p ------- 150 + 560 = 710

2p ------- 320

1p ------- 160

1u ------- 390 - 160 = 230

230 - 150 = 80 (boys moved)

230 - 180 = 50 (girls moved)

Ans : 80 boys and 50 girls.

- alfretztay
- KiasuGrandMaster
**Posts:**1199**Joined:**Sun Sep 12,**Total Likes:**5

### Re: Q&A - PSLE Math

voltes5 wrote:alfretztay,alfretztay wrote:I would solve the above problem as follows :voltes5 wrote:Thanks in advance for the help.

Sally bought some chocolates and gave half of them to Mabel. Sally also bought some lollipops and gave half of them to Mabel. Mabel ate 7 lollipops and Sally ate 16 chocolates.

After that, the number of lollipops and chocolates Mabel had were in the ratio 1:8 and the number of lollipops and chocolates Sally had were in the ratio 1:5. How many lollipops did Sally buy at first?

Answer says 48 but I could not understand how to arrive at it.

For chocolate,

Sally : 2u - 1u - 16 = 1u - 16

Mabel : +1u

For lollipops,

Sally : 2p - 1p = 1p

Mabel : +1p - 7

For Mabel,

(1p - 7) x 8 ------- 1u

8p - 56 ------- 1u

For Sally,

1p x 5 ------- 1u - 16

5p + 16 ------- 1u

8p - 56 ------- 5p + 16

3p ------- 72

1p ------- 72/3 = 24

2p ------- 2 x 24 = 48

Ans : 48 lollipops.

What does this mean?

(1p - 7) x 8 ------- 1u

From "after that, the number of lollipops and chocolates Mabel had were in the ratio 1:8",

number of lollipops(1p - 7)/number of chocolates(1u) = 1/8

number of lollipops(1p - 7) x 8 = number of chocolates(1u) x 1

### Re: Q&A - PSLE Math

alfretztay,alfretztay wrote:I would solve the above problem as follows :NerdyMath wrote:Similar to 2009 PSLE mathematics question.voltes5 wrote:Thanks in advance for the help.

Sally bought some chocolates and gave half of them to Mabel. Sally also bought some lollipops and gave half of them to Mabel. Mabel ate 7 lollipops and Sally ate 16 chocolates.

After that, the number of lollipops and chocolates Mabel had were in the ratio 1:8 and the number of lollipops and chocolates Sally had were in the ratio 1:5. How many lollipops did Sally buy at first?

Answer says 48 but I could not understand how to arrive at it.

Let's start by doing it backwards.

Mabel

L[]

c[][][][][][][][][16]

Sally

L [][7]

C [][7][][7][][7][]7][][7]

Reason why there is an extra 7 is because Sally didnt eat 7 lollipop.

Reason Why there is an extra 16 is because Mabel didn't eat 16 chocolate.

Let's equate.

8u - 16 = 5u + 7x5

8u - 16 = 5u + 35

3u = 35+16

1u = 17

17 + 7 = 24

24X 2= 48

Answer:48

Solved by DS.

For chocolate,

Sally : 2u - 1u - 16 = 1u - 16

Mabel : +1u

For lollipops,

Sally : 2p - 1p = 1p

Mabel : +1p - 7

For Mabel,

(1p - 7) x 8 ------- 1u

8p - 56 ------- 1u

For Sally,

1p x 5 ------- 1u - 16

5p + 16 ------- 1u

8p - 56 ------- 5p + 16

3p ------- 72

1p ------- 72/3 = 24

2p ------- 2 x 24 = 48

Ans : 48 lollipops.

What does this mean?

(1p - 7) x 8 ------- 1u

### Re: Q&A - PSLE Math

Sally bought some chocolates and gave half of them to Mabel. Sally also bought some lollipops and gave half of them to Mabel. Mabel ate 7 lollipops and Sally ate 16 chocolates.

After that, the number of lollipops and chocolates Mabel had were in the ratio 1:8 and the number of lollipops and chocolates Sally had were in the ratio 1:5. How many lollipops did Sally buy at first?

Answer says 48 but I could not understand how to arrive at it.

Code: Select all

```
Sally Mabel
L : C L : C
-16 -7
1u : 5u 1p : 8p
```

Choc, 5u+16 = 8p

5u = 8p -16 -----(2)

(1) X5, 5u = 5p + 35 ---(3)

(2) = (3), both are 5u

8p - 16 = 5p + 35

3p = 51

p = 17

L = 1P+7= 24

At first, before she gave half to MAbel, she had 24 X 2 = 48

- alfretztay
- KiasuGrandMaster
**Posts:**1199**Joined:**Sun Sep 12,**Total Likes:**5

### Re: Q&A - PSLE Math

From "after that, the number of lollipops and chocolates Mabel had were in the ratio 1:8",voltes5 wrote:alfretztay,alfretztay wrote:I would solve the above problem as follows :

Sally bought some chocolates and gave half of them to Mabel. Sally also bought some lollipops and gave half of them to Mabel. Mabel ate 7 lollipops and Sally ate 16 chocolates.

After that, the number of lollipops and chocolates Mabel had were in the ratio 1:8 and the number of lollipops and chocolates Sally had were in the ratio 1:5. How many lollipops did Sally buy at first?

Answer says 48 but I could not understand how to arrive at it.

For chocolate,

Sally : 2u - 1u - 16 = 1u - 16

Mabel : +1u

For lollipops,

Sally : 2p - 1p = 1p

Mabel : +1p - 7

For Mabel,

(1p - 7) x 8 ------- 1u

8p - 56 ------- 1u

For Sally,

1p x 5 ------- 1u - 16

5p + 16 ------- 1u

8p - 56 ------- 5p + 16

3p ------- 72

1p ------- 72/3 = 24

2p ------- 2 x 24 = 48

Ans : 48 lollipops.

What does this mean?

(1p - 7) x 8 ------- 1u

number of lollipops(1p - 7)/number of chocolates(1u) = 1/8

number of lollipops(1p - 7) x 8 = number of chocolates(1u) x 1