Q&A - PSLE Math

[2632parent]

Urgently need your help on the following 2 questions


1) If Mrs Tan transfers 1 girl from the Math club to the English club. 1/7 of the remaining members in the Math club will be girls. However if she transfer 2 boys instead to the English club then 1/5 of the remaining pupils in the Math club will be girls. What is the total number of boys and girls in the Math club.

2) Faizai had a total of 461 male and female goldfish. He gave away 60% of the male goldfish and 1/3 of the goldfish for the charity fund raising project. Then he bought 30 female goldfish. As a result, the number of female goldfish he had was 25% the number lof male goldfish left.
a) How many male goldfish did he have at first?

b) The next day, 16 male goldfish and 14 female goldfish died. What percentage of goldfish left was the female goldfish?


Many many thanks

[lakshmi v]

Can anyone help fast?


Mr Ang had 600 red and blue balloons altogether. After he sold 20% of his red balloons and bought another 60 blue balloons, the number of blue balloons was 2/5 the number of red balloons. How many red than blue balloons were there at first?

Thanks in advance.

[paranoid]

Ready2WORK:

paranoid:

The figure below is made up of Squares EFGH and PQRS, a circle and two identical semicircles. J and K are the midpoints of PQ and RQ respectively.

P, Q, R, and S are the midpoints of EF, FG, GH and EH respectively.

Use the calculator value of pi to find the total area of the shaded parts, correct to 2 decimal places.

http://i48.tinypic.com/339k95z.png\">

Thanks in advance.

Please note that you did not indicate the dimensions of the figure.
However, the steps to find out the answer are as follows.
http://i45.tinypic.com/awykh1.png\">
Therefore, the working is:
(Big square-small square/8)+(Circle-small square/4)

thanks. :thankyou:

[match3frog]

tianzhu:

fantasy1:

Hi


Can anyone help me with these 2 problems?

1)Last month,MAy spent 1/4 of her income on transport, 45% on food and saved the rest.
Her income was increased by 1/10 in this month.
Spent the same amount on transport but increased her savings by 30%.
She saved $780 this month.
(a) How much did she spend on food this month?


2)7 apples cost as much as 2 mongoes. 5 oranges cost as much as a mango.
Find the ratio of the cost of one applke to the cost of one mango to the cost of one orange.

Hi

1)

A neat way is to use MD.

Consider the savings this month.

13u ------ 780

10u ------- 600 (last month’s savings)

Last month

25% ------- transport

45% ------- food

30% -------- food

30% -------- 600

10% ------- 200

Income last month ------- 100% ------- 2000

Income this month ------- 2200

Transport ------- 500 (same amount)

Savings ------- 780

Food’s spending ------- 2200 – 500-780 ------- 920

2)

Use 70 units for the cost.

1 apple ------- 10 units

1 mango ------ 35 units

1 orange -------- 7 units

A : M: 0 ------- 10:35:7

Best wishes

Hi for Q2,

Can my workings be as follows:

7 apples=2 mangoes
5 oranges = 1 mango, therefore 10 oranges = 2 mangoes

A : M : O
7 : 2 : 10 (ANS)

Thanks.

[tianzhu]

2632parent:

Urgently need your help on the following 2 questions


1) If Mrs Tan transfers 1 girl from the Math club to the English club. 1/7 of the remaining members in the Math club will be girls. However if she transfer 2 boys instead to the English club then 1/5 of the remaining pupils in the Math club will be girls. What is the total number of boys and girls in the Math club.

Hi

A neat way is to use MD
.
Due to time constraints, I’ll give you some pointers.

If Mrs Tan transfers 1 girl from the Math club to the English club. 1/7 of the remaining members in the Math club will be girls.

Girls ----- 1 box + 1

Boys ------ 6 boxes

However if she transfer 2 boys instead to the English club then 1/5 of the remaining pupils in the Math club will be girls.

Girls ------ (1 box + 1)

Boys ------ (1 box + 1) + (1 box + 1) + (1 box + 1) + (1 box + 1) + 2

Compare the two cases

6 boxes ------ 4 boxes + 6

2 boxes ----- 6

1 box ------ 3

Girls ------ 4

Boys ------ 18

Total ------- 22

Hope this helps.

Best wishes

[MathIzzzFun]

match3frog:

tianzhu:

[quote=\"fantasy1\"]Hi


Can anyone help me with these 2 problems?

1)Last month,MAy spent 1/4 of her income on transport, 45% on food and saved the rest.
Her income was increased by 1/10 in this month.
Spent the same amount on transport but increased her savings by 30%.
She saved $780 this month.
(a) How much did she spend on food this month?


2)7 apples cost as much as 2 mongoes. 5 oranges cost as much as a mango.
Find the ratio of the cost of one applke to the cost of one mango to the cost of one orange.

Hi

1)

A neat way is to use MD.

Consider the savings this month.

13u ------ 780

10u ------- 600 (last month’s savings)

Last month

25% ------- transport

45% ------- food

30% -------- food

30% -------- 600

10% ------- 200

Income last month ------- 100% ------- 2000

Income this month ------- 2200

Transport ------- 500 (same amount)

Savings ------- 780

Food’s spending ------- 2200 – 500-780 ------- 920

2)

Use 70 units for the cost.

1 apple ------- 10 units

1 mango ------ 35 units

1 orange -------- 7 units

A : M: 0 ------- 10:35:7

Best wishes

Hi for Q2,

Can my workings be as follows:

7 apples=2 mangoes
5 oranges = 1 mango, therefore 10 oranges = 2 mangoes

A : M : O
7 : 2 : 10 (ANS)

Thanks.[/quote]the ratio A:M:O=7:2:10 means orange is the most expensive and mango the cheapest, which is incorrect.

we can also used equal fraction method to do:
7 A= 2 M= 10 O
so 70/10 A = 70/35 M = 70/7 O
denominators will the respective ratio
A:M:O = 10:35:7

cheers.

[the5mate]

PSLE wont test you very hard questions its on simple application skills and knowledge of the skills taught in primary school…

[tianzhu]

2632parent:

2) Faizai had a total of 461 male and female goldfish. He gave away 60% of the male goldfish and 1/3 of the goldfish for the charity fund raising project. Then he bought 30 female goldfish. As a result, the number of female goldfish he had was 25% the number lof male goldfish left.

a) How many male goldfish did he have at first?

b) The next day, 16 male goldfish and 14 female goldfish died. What percentage of goldfish left was the female goldfish?

Hi

I’ll just give you some pointers.

A neat way is to use MD.

Male GF

Gave away ------- 6 units (bigger box)

Left ------- 4 units

Female GF

Gave away ------- 1 part (smaller box)

Left ------- 2 parts

Then he bought 30 female goldfish. As a result, the number of female goldfish he had was 25% the number of male goldfish left.

2 parts + 30 ------ 1 unit

20 parts + 300 + 3 parts ------- 461

1 part ------ 7

Number of male GF@first ------- 20 parts + 300 ------- 440

Number of FGF ------- 21

I think you can carry on from here.

Best wishes

[2632parent]

Thank you tianzhu for the solution and I understand the method.

[Joe Ye Di]

ans: 22.5m/s