Q&A - PSLE Math

[Michaelia0816]

13) The ratio of Joe’s allowance to Rachel’s allowance was 4:3. After Joe and Rachel were given $15 and $8 respectively, the ratio of Joe’s allowance to Rachel’s allowance became 3:2. How much allowance did Joe have at first?

[Michaelia0816]

14) There were some men and woman in the train. Aft 30 men alighted from the train, the percentage of woman increased from 30% to 45%. How many people were there in the train after 30 men had alighted?

[Michaelia0816]

16) Daniel had 40% as many marbles as Ethan. Daniel gave away 8 marbles to his brother and Ethan lost 40 marbles of his marbles in a game. Then, Daniel had half as many as Ethan.

A) How many marbles did Daniel have at first?
B) How many marbles did Ethan have at first?

[Winx5015]

There were 90 more males than females at an exhibition hall. After 80% of the males and 30% of the females left the hall, there were twice as many females as males that remained. Find the total number of people at the hall at first.


Thanks.

[tianzhu]

Winx5015:

There were 90 more males than females at an exhibition hall. After 80% of the males and 30% of the females left the hall, there were twice as many females as males that remained. Find the total number of people at the hall at first.


Thanks.

Hi

You may use MD or work with units.

At first

Males -------- 10 units + 90
Females -------- 10 units

80% of the males and 30% of the females left the hall

Males (remained) -------- 2 units + 18
Females (remained) -------- 7 units

There were twice as many females as males that remained.

7 units -------- 4 units + 36

1 unit ------- 12

Number of people @ first -------- (20*12) +90 --------330

Best wishes

[tianzhu]

Michaelia0816:

16) Daniel had 40% as many marbles as Ethan. Daniel gave away 8 marbles to his brother and Ethan lost 40 marbles of his marbles in a game. Then, Daniel had half as many as Ethan.

A) How many marbles did Daniel have at first?
B) How many marbles did Ethan have at first?

Hi

You may use “Units and Parts”

At first
Daniel : Ethan -------- 2units :5 units

Change
Daniel : Ethan -------- -8 : -40

In the end
Daniel : Ethan -------- 1 part :2 parts

Equalise the parts

2 units – 8 ------- 1 part
(x2)
4 units – 16 -------- 2 parts

4 units – 16 -------- 5 units – 40
1 unit ------- 24

Daniel@first -------- 48
Ethan@ first -------120

You may apply the same method for Q13.

Best wishes

[tianzhu]

Michaelia0816:

14) There were some men and woman in the train. Aft 30 men alighted from the train, the percentage of woman increased from 30% to 45%. How many people were there in the train after 30 men had alighted?

Hi

The number of women stays the same before and after. Make the number of units for women the same.

At first
Men ------- 7 ---------- 21
Women ------- 3 --------- 9

In the end
Men ------- 11
Women ------- 9

10 units ------- 30
1 unit -------- 3

20*3 -------- 60 (number of people@end)

Best wishes

[kklau]

small:

tianzhu:

[quote=\"kklau\"]Hi,


Re-post and I would be very much appreciate that anyone could help to provide solution to this P6 maths question.

The diagram below 2 quadrants and a circle in a square of edge 10cm. Find the area of the shaded region (Take π = 3.14)

http://i47.tinypic.com/10fv18n.png\">

Thank you.

Best Regards.

Hi

Could you share where is your question from?

I've seen one similar question some years ago, but the shaded areas differs slightly.

Best wishes

http://farm8.staticflickr.com/7089/7152307519_7fa3e70673_z.jpg\">

Hi kklau,

I hope my working will not confuse you.

http://i47.tinypic.com/33x78nn.jpg\">[/quote]Hi,

Many thanks for your solution and really appreciate your help.

Cheers.

:thankyou:

[tianzhu]

Michaelia0816:

12) An empty cup was 75g. A cup with objects A and B was 300g. A cup with objects A and C was 375g. A cup with objects B and C was 350g


A) What was the total mass of objects A,B and C?
B) Find the mass of object A?

Hi

A + B -------- 225
A + C ---------300
B + C -------- 275


A+B+C -------- (225+300+275)/2 ------- 425

A ------- 425 -275 ------150

Best wishes

[kklau]

tianzhu:

Hi kklau


Good Morning.

What I am sharing is one similar question which my kid had done years ago.

If the question is shaded as I’ve drawn, then you may follow the steps as shown in this slide.I've attempted to breakdown the composite figure into familiar shapes.Please get your child to work out the other details.

Please take note that this is a possible way, there are alternatives.

Usually, the calculations in questions on composite figures are quite neat, just applying the formulae and pressing the calculators. But, the difficulties many students faced are visualising and rearranging the shapes into familiar shapes. This is the part which tripped many students.

You may also refer to small’s solution.

Hope this helps.

Best wishes

http://farm8.staticflickr.com/7041/7154653294_de8b0cc591_z.jpg\">

Hi tianzhu,

Many thanks for your solution and really appreciate your help.

Cheers.

:thankyou: & :thankyou: