Q&A - PSLE Math

[Winx5015]

Hi MathIzzzFun,


Thanks for solving my questions.

Regards

[anneshirleygilbert]

Can somebody please help with this question?


Four files cost as much as 3 storybooks. Five files cost $7.50 more than 2 storybooks. Mary spent $30 on an equal number of files and storybooks. How many files did she buy?

We tried to find cost of 1 book and cost of 1 file, and got terribly muddled. There must be an easier way. Can somebody help?

[MathIzzzFun]

anneshirleygilbert:

Can somebody please help with this question?


Four files cost as much as 3 storybooks. Five files cost $7.50 more than 2 storybooks. Mary spent $30 on an equal number of files and storybooks. How many files did she buy?

We tried to find cost of 1 book and cost of 1 file, and got terribly muddled. There must be an easier way. Can somebody help?

Hi

1 file --> 3 units
1 story book --> 4 units
1 file + 1 story book --> 7 units

5 files --> 15 units
2 storybooks --> 8 units
7 units = $ 7.50

So, 1 file + 1 story book = $ 7.50
$ 30 / $ 7.50 = 4

Mary bought 4 files and 4 story books

cheers.

[anneshirleygilbert]

Thanks a bunch, MathIzzzFun. You do make it seem so simple.

[MathIzzzFun]

anneshirleygilbert:

Thanks a bunch, MathIzzzFun. You do make it seem so simple.

u r welcome

cheers.

[2DMommy]

Please help me with these questions :


1) In March,the total savings of Andy, Henry, Roy and Zack was $2498. In April, the savings of the four boys became equal after Andy’s savings decreased by $65. Henry’s savings doubled and Roy’s savings increased by
$129. Zack’s savings remained the same. What was Roy’s savings in March ?

2)75% of the children in the stadium were girls. After 52 girls and 4 boys left, the remaining children formed groups of 8. In each group, there were 3 boys. How many children were there in the stadium at first ?

3)A flask is 1/3 filled with chocolate powder. A teapot twice as large as the flask, is 1/4 filled with chocolate powder. Then the flask and the teapot are each filled with water completely and all the contents are mixed together into a chocolate drink. What fraction of the chocolate drink is the chocolate powder?

Thank you.

[tianzhu]

2DMommy:

2)75% of the children in the stadium were girls. After 52 girls and 4 boys left, the remaining children formed groups of 8. In each group, there were 3 boys. How many children were there in the stadium at first ?

Hi

You may use \"Units and Parts\"

At first
Boys: Girls ------- 1u:3u

Change
Boys: Girls ------- -4:-52

In the end
Boys: Girls ------- 3p:5p

Equalise the parts.

(1u - 4) ----- 3p
(x5)
5u - 20 ------ 15p

(3u - 52) ----- 5p
(x3)
9u - 156 ------15p

5u - 20 ----- 9u - 156
4u ----- 136
1u ------ 34

Number of children in the stadium at first ------ 4*34 ------ 136

Best wishes

[tianzhu]

2DMommy:

3)A flask is 1/3 filled with chocolate powder. A teapot twice as large as the flask, is 1/4 filled with chocolate powder. Then the flask and the teapot are each filled with water completely and all the contents are mixed together into a chocolate drink. What fraction of the chocolate drink is the chocolate powder?

Hi

To avoid working with decimals, use 12 units (3 and 4)

Flask(chocolate) ------- 2 units (1/3 of 6 units)
Teapot(chocolate) ------- 3 units (1/4 of 12 units)

Chocolate powder ------ 5 units

Total volume ------- 6+12 ------ 18 units

Fraction of drink which is chocolate --------- 5/18

Best wishes

[tianzhu]

2DMommy:

In March,the total savings of Andy, Henry, Roy and Zack was $2498. In April, the savings of the four boys became equal after Andy's savings decreased by $65. Henry's savings doubled and Roy's savings increased by $129. Zack's savings remained the same. What was Roy's savings in March ?

Hi

You may use MD.

In April

Andy ------ 2 units
Henry ------ 2 units
Roy ------ 2 units
Zack ------ 2 units

In March

Andy ------ 2 units + 65
Henry ------ 1 unit
Roy ------ 2 units - 129
Zack ------ 2 units

7 units ------2498+129-65 -------- 2562
1 unit ------ 366

Roy ------ (2*366) – 129 ------ 603

Best wishes

[2DMommy]

Thank you tianzhu.


I have another question :

5 workers take 3 hour 40 mins to paint a house if every worker paints at the same rate and all start and end at the same time. If one of them leaves after painting for an hour, how long will it take the remaining workers to complete the job after the worker has left ?