Q&A - PSLE Math

[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.

[ozora]

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 --> 4 x 25 x $0.20 + 1 x 25 x $ 0.50 = $ 32.50

cheers.

thanks MathsIzzFun. got it. is there an error in : 4 x 25 x $0.20 ? should it be 2 x25 x0.2?
do we ignore the After a few rounds, he found that there are eighteen 20 cents coins and 1 50 cents coin left

[MathIzzzFun]

ozora:

MathIzzzFun:

[quote=\"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 --> 4 x 25 x $0.20 + 1 x 25 x $ 0.50 = $ 32.50

cheers.

thanks MathsIzzFun. got it. is there an error in : 4 x 25 x $0.20 ? should it be 2 x25 x0.2?
do we ignore the After a few rounds, he found that there are eighteen 20 cents coins and 1 50 cents coin left[/quote]Thanks for pointing out the error.
The 'After a few rounds, he found that there are eighteen 20 cents coins and 1 50 cents coin left' is needed because this gives us the leftover coins after removing in the ratio of 4:3.

using units/parts, we get
at first, 20c:50c -> 2u : 1u
Coins removed, 20c:50c -> 4p : 3p
18 20c and 1 50c left, so
2u - 4p = 18
1u - 3p = 1
and then solving for u/p

cheers

[starfish53]

Can anyone help me with the following question?



1) A blouse cost 4/5 as much as a dress. Serena spent 3/8 of her money on 3 blouses. She also bought 2 dresses. What fraction of her money did she spend altogether?


2) Ivan divided 64 guppies into 4 bowls A to D. 7 guppies were transferred from Bowl A to Bowl B, 3 guppies were moved from Bowl C to Bowl B and 9 guppies were moved from Bowl C to Bowl D. All the bowls then had an equal number of guppies. Express in ratio the sum of the number of guppies in Bowl A and B at first to the sum of the number of guppies in Bowl C and D at first.


Thanks in advance.

[Maths Hub]

starfish53:

Can anyone help me with the following question?



1) A blouse cost 4/5 as much as a dress. Serena spent 3/8 of her money on 3 blouses. She also bought 2 dresses. What fraction of her money did she spend altogether?


2) Ivan divided 64 guppies into 4 bowls A to D. 7 guppies were transferred from Bowl A to Bowl B, 3 guppies were moved from Bowl C to Bowl B and 9 guppies were moved from Bowl C to Bowl D. All the bowls then had an equal number of guppies. Express in ratio the sum of the number of guppies in Bowl A and B at first to the sum of the number of guppies in Bowl C and D at first.


Thanks in advance.

1) 3 blouses-->3/8
1 blouse--> 1/8
1 dress-->5/4 X 1/8= 5/32
2 dresses--> 5/16
3 blouses + 2 dresses--> 3/8+5/16 = 11/16

2) This is a working backwards question. The most important information is \"All the bowls then had an equal number of guppies. \"

End
A:B:C:D
16:16:16:16

Before \"9 guppies were moved from Bowl C to Bowl D\"
A:B:C:D
16:16:25:7

Before \"3 guppies were moved from Bowl C to Bowl B\"
A:B:C:D
16:13:28:7

Before \"7 guppies were transferred from Bowl A to Bowl B\"
A:B:C:D
23:6:28:7

Therefore:
A+B:C+D
29:35

Hope that helps.