Q&A - PSLE Math

[notfreemom]

notfreemom:

Please help.

Red Swastika Prelim 2012
Paper 2 Q 17.
A shopkeeper had some blue and red pens in his book shop. There were twice as many red pens as blue pens. The shopkeeper sold the pens in bundles of 2 red pens and 3blue pens. After selling all the blue pens, he still had 120 red pens left. How many pens did he have in his bookshop at first?

Answer 270
thanks.

Oh I just managed to figure it myself. Thanks.

[dicoyote]

The cost of 3 apples is the same as that of 2 oranges. The total cost of 4 apples and 3 oranges is $3.40. Mrs Tan bought 7 apples and 5 oranges. How much did she pay for apples and oranges altogether?


I have the answer, which is $5.80, not able to work it out though, thanks in advance

[MathIzzzFun]

dicoyote:

The cost of 3 apples is the same as that of 2 oranges. The total cost of 4 apples and 3 oranges is $3.40. Mrs Tan bought 7 apples and 5 oranges. How much did she pay for apples and oranges altogether?


I have the answer, which is $5.80, not able to work it out though, thanks in advance

Hi

3 apples = 2 oranges --> 6 units

1 apple --> 2 units
1 orange --> 3 units

4 apples + 3 oranges --> 8 units + 9 units = 17 units
17 units --> $ 3.40
1 unit --> $0.20

7 apples + 5 oranges --> 14 units + 15 units = 29 units --> $ 5.80

cheers.

[AJH]

Hi.


In January, 70% of the pupils in a private school were girls and the rest were boys.
In March, 525 more pupils joined the private school and the percentage of girls increased to 80% while the number of boys tripled. How many girls joined the private school in March?

Is the ans. 75?

Thank you.

[tianzhu]

AJH:

Hi.


In January, 70% of the pupils in a private school were girls and the rest were boys.
In March, 525 more pupils joined the private school and the percentage of girls increased to 80% while the number of boys tripled. How many girls joined the private school in March?

Is the ans. 75?

Thank you.

Hi

I think the answer is 435 girls.

January

Boys ------ 3 units
Girls ------ 7 units

March

Boys ------ 9 units (tripled) ------ 20%
Girls ------ 36 units ------- 80%

45 – 10 -------- 35

35 units ------- 525

1 unit ------- 15

Increase in units for girls in March ------- 36 – 7 ------- 29

Number of girls who joined in March ------ 29*15 ------- 435

Best wishes

[MathIzzzFun]

AJH:

Hi.


In January, 70% of the pupils in a private school were girls and the rest were boys.
In March, 525 more pupils joined the private school and the percentage of girls increased to 80% while the number of boys tripled. How many girls joined the private school in March?

Is the ans. 75?

Thank you.

Hi

At first,

Girls--> 14u
Boys --> 6u
Total 20u

In Mar,
Boys --> 18u --- 20%
Total number of girls & boys in Mar --> 100/20 * 18u =90u, total joined in Mar --> 70u
Girls ---> 72u, girls joined in Mar --> 58u

70u--> 525
58*525/70 =435

435 girls joined in Mar.

cheers.

[kyp71]

Can someone please help to solve the below pie chart problem. http://i45.tinypic.com/264s8ra.jpg\">

[tianzhu]

Hi


3 units (3/7) ------ 5+7+12 ------- 24

1 unit --------- 8

Number of pupils who like lemon tea -------2*8 ------16

Total number of pupils ------- 56

Fraction of pupils who like Fanta Grape ------- 7/56 ------1/8

Best wishes

[kyp71]

tianzhu:

Hi


3 units (3/7) ------ 5+7+12 ------- 24

1 unit --------- 8

Number of pupils who like lemon tea -------2*8 ------16

Total number of pupils ------- 56

Fraction of pupils who like Fanta Grape ------- 7/56 ------1/8

Best wishes

Hi TianZhu,

I do not understand why 3 units ------ 5+7+12 ? How did not derive on this ??

[tianzhu]

kyp71:

Hi TianZhu,

I do not understand why 3 units ------ 5+7+12 ? How did not derive on this ??

Hi

Lemon tea ------- 2/7

Coke ------- 2/7 + 5

The whole of the pie chart is 7/7 or 1 whole.

Taking out 4/7, the rest (3/7) or 3 units ------ 5+7+12

Best wishes