Q&A - PSLE Math

[TheSolver]

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?

Girls-->180+210=390
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

[voltes5]

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?

Average difference -- > 146-143=3

143-128 = 15

15/3 = 5

5 + 1 = 6.

Answer: 6

Solved by DS.

Thank you for your answer. May I ask what is the meaning of (143-128)?

[alfretztay]

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?

Before :
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.

[voltes5]

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.

Similar to 2009 PSLE mathematics question.


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.

I would solve the above problem as follows :

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.

alfretztay,

What does this mean?
(1p - 7) x 8 ------- 1u

[alfretztay]

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?

Girls-->180+210=390
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

Before :
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]

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.

I would solve the above problem as follows :

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.

alfretztay,

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

[voltes5]

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.

Similar to 2009 PSLE mathematics question.


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.

I would solve the above problem as follows :

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.

alfretztay,

What does this mean?
(1p - 7) x 8 ------- 1u

[Ender]

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.

Code: Select all

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

Lollipops, 1u = 1p+7 -------(1)
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]

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.

I would solve the above problem as follows :

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.

alfretztay,

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

[hoddle]

Hi

Please solve the below. Thks.