Q&A - PSLE Math

[tianzhu]

Mary Joy:

1.A swimming club has 30 girls and a no of boys.tHe number of boys increased by 15% to 46. And the no of girls decreased by 30%.what is the overall increase or decrease in the club's membership?


Please help me to solve this Qn.Thank you :thankyou:

Hi

You may wish to draw a model.

Boys

115% ----- 46
100% ------ 40

Girls

100% ------ 30
70% ----- 21

Number of members at first ------ 70 (40+30)

Number of members in the end ------ 67 (46+21)

Hence, overall decrease of 3 members

Best wishes

[ftwm]

pls help e Q;


The ratio of the numbers of cars to the number of vans in a carpark was 3 : 4. After 6 more cars entered the carpark and 5 vans left the carpark, there was an equal number of cars and vans in the carpark. How many cars were there in the carpark at first?

Tq

[tianzhu]

starfish53:

1) Can anyone help me with the following question? 800 more females than males went for a workshop on the first day. On the second day, the number of females decreased by 10% while the number of males increased by 40%. 3641 people went to the workshop on the second day.


a) How many females were there at the workshop on the second day?

b) Of each participant for the workshop had to pay $8, how much money was collected from the workshop on the first day?

Hi

You may use MD or work using units.

First day

Females ------ 10 units + 800
Males ----- 10 units

Second day

Females ------ 9 units + 720
Males ----- 14 units

23 units + 720 ------ 3641

1 unit ------ 127

Number of females at workshop on the second day ------- 9 units + 720 -------1863

Number of participants@first day ------- 20 units + 800 ------- 3340

Amount collected ------ 3340*8 ----- 26720

Best wishes

[ftwm]

Q.


In the figure, not drawn to scale, the ratio of the area of the triangle to the area of the square to the are of the rectangle is 3 : 4 : 10. If 1/4 of the square is shaded, what is the ratio of the area of the shaded part to the area of the unshaded part of the figure?

tq

[MathIzzzFun]

starfish53:

1) Can anyone help me with the following question?


2) Nick had some $5 and $10 notes in his wallet. He had a total of 60 pieces of notes at first. He used half of the number of $5 notes and his uncle gave him another twelve $10 notes. After that, the number of $10 notes he had was 2/3 of the remaining numer of $5 notes he had left. How much money did he have at first?

Thanks in advance.

In the end,

Number of $5 notes --> 3 units
Number of $10 notes --> 2 units

At first,
Number of $5 notes --> 3 units x 2 = 6 units
Number of $10 notes --> 2 units - 12

Total number of notes at first,

8 units - 12 = 60
1 unit --> 9

At first,
value of $5 notes --> 6 x 9 x $5 = $270
value of $10 notes --> (2 x 9 -12) x $10 = $60
Total $330

cheers.

[tianzhu]

ftwm:

pls help e Q;


The ratio of the numbers of cars to the number of vans in a carpark was 3 : 4. After 6 more cars entered the carpark and 5 vans left the carpark, there was an equal number of cars and vans in the carpark. How many cars were there in the carpark at first?

Tq

Hi

One possible way is to use UP.

Before

Car: Van ------3u:4u

Changes

Car: Van ------ 6: - 5

After

Car: Van ------1p:1p

3u + 6 ------ 4u - 5

1u ---- 11

Number of cars@first ----- 33

For more practices

Math Questions involving Changed Quantities

http://www.kiasuparents.com/kiasu/content/math-questions-involving-changed-quantities

Best wishes

[MathIzzzFun]

ftwm:

pls help e Q;


The ratio of the numbers of cars to the number of vans in a carpark was 3 : 4. After 6 more cars entered the carpark and 5 vans left the carpark, there was an equal number of cars and vans in the carpark. How many cars were there in the carpark at first?

Tq

http://i42.tinypic.com/15d3mhd.png\">

1 unit --> 11

Cars, at first --> 33

cheers.

[Oldschool]

ftwm:

Q.


In the figure, not drawn to scale, the ratio of the area of the triangle to the area of the square to the are of the rectangle is 3 : 4 : 10. If 1/4 of the square is shaded, what is the ratio of the area of the shaded part to the area of the unshaded part of the figure?

tq

Hi,

Since there is only \"one\" shaded area, I will assume the figure look like this,

http://i43.tinypic.com/33xgas2.jpg\">

Regards

[ozora]

need help in this question.

Sam has a bag of 20 cents coins and a bag of 50 cents coins. The number of 20 cents coins is double the number of 50 cents coins.
Sam takes out three 50 cents coins and four 20 cents coins each time.
After a few rounds, he found that there are eighteen 20 cents coins and 1 50 cents coin left. How much money did Sam have?
thanks

[MathIzzzFun]

ozora:

need help in this question.

Sam has a bag of 20 cents coins and a bag of 50 cents coins. The number of 20 cents coins is double the number of 50 cents coins.
Sam takes out three 50 cents coins and four 20 cents coins each time.
After a few rounds, he found that there are eighteen 20 cents coins and 1 50 cents coin left. How much money did Sam have?
thanks

Total number coins - number of coins left = number coins removed

At first,
number of 20c coins : 50c coins --> 2u : 1u

Coins removed,
number of 20c coins : 50c coins
--> 2u - 18 : 1u -1
= 4 : 3

cross multiply/equalize:

6u - 54 = 4u - 4
1u --> 25

total amount of money --> 2 x 25 x $0.20 + 1 x 25 x $ 0.50 = $ 22.50

cheers.