Q&A - PSLE Math

[tianzhu]

2DMommy:

Need help again,


1) Danny and Richard earned a total of $3850. Richard earned $1850 more than Danny. Danny earned $5 more than Richard each day and Richard worked 3 times as many days as Danny. How much did Richard earn each day

Hi

Richard ----- 2850

Danny ------ 1000

Richard ------ 3 units

2850/3 ------ 950

1000 – 950 ----- 50

Number of days ------- 50/5 ------- 10

Danny ------ 1000/10 ------- 100

Richard ------ 95

Best wishes

[tianzhu]

elkniwt:

Hello,


Need help in this qn from Henry Park 2011 Prelim :

http://i48.tinypic.com/2i7qozm.jpg\">

Thanks!!

Hi

Please refer to earlier discussion.

Best wishes

http://www.kiasuparents.com/kiasu/forum/viewtopic.php&f=69&t=280&p=778481

But I think, there are added shaded portions inside the image as this is the duplicated set.

I’d go for

½ of square (12*12) – ½ of semicircle (r6) ------- 15.45

Area of 1 quadrant (r6) -------- 28.27

Total area ------ 43.72 (15.45 + 28.27)

Best wishes

[Michaelia0816]

So my answer is correct, 960, Thanks!

[Michaelia0816]

Also, thank for the square question!

[tianzhu]

dora miscq:

Mr and Mrs Leong left their house at the same time but travel in opposite directions.

Mr Leong travelled towards Bedok while Mrs Leong headed for Kallang.
Mrs Leong drove at a speed which was 10 km/h slower than Mr Leong.
30 minutes later, when Mr Leong reached Bedok, they were 95km apart.
How far did Mrs Leong travel when Mr Leong reached Bedok?

Hi

As in any Speed question, start with a simple diagram.

In 1h, Mrs Leong covered 10 km less than Mr Leong.

In 30 minutes, Mrs Leong covered 5km less than Mr Leong.

1unit (Mrs Leong) + 1 unit + 5 (Mr Leong) ------ 95

1 unit ------- 45

Mrs Leong travelled 45 km

Best wishes

[fightingmom]

Hi,


Please help with the following 2 questions:

(1) 450 people took part in a race. 97 of them were children and the rest were adults. 3/5 of the women and 3/4 of the men were married while the rest of them were singles. There were 15 more married men than married women.

(a) How many singles were there ?
(b) what fraction of the people who took part in the race were men ?



(2) in 2007, there were 90 more girls than boys in ABC school. In 2008, there were 1/3 fewer girls and the number of bigs increased by 5/9, resulting in a total of 660 pupils.

(a) what fraction of the pupils in 2007 were boys?
Express your answer in its simplest form

(b) in 2009, the number of girls increased while the number of boys remained the same in 2008. The ratio of the number of girls to the number of boys in 2009 was the same as the ratio in 2007.
How many pupils were there in 2009?


TIA !

[tianzhu]

fightingmom:

Hi,


Please help with the following 2 questions:

(1) 450 people took part in a race. 97 of them were children and the rest were adults. 3/5 of the women and 3/4 of the men were married while the rest of them were singles. There were 15 more married men than married women.

(a) How many singles were there ?
(b) what fraction of the people who took part in the race were men ?

Hi

This question has been discussed before.

A neat way is to use MD.Replace the W amd M with boxes of different sizes.

450-97 ----- 353
3M-3W ------15
M is 5 more than W

4W + 20 + 5W ------353
1W ------- 37
1M -------42

a)Singles --------- (37*2)+42 ------116
b)Men -------42*4 ------168
168/450 ------ 28/75

Best wishes

[tianzhu]

fightingmom:

(2) in 2007, there were 90 more girls than boys in ABC school. In 2008, there were 1/3 fewer girls and the number of bigs increased by 5/9, resulting in a total of 660 pupils.

(a) what fraction of the pupils in 2007 were boys?
Express your answer in its simplest form

(b) in 2009, the number of girls increased while the number of boys remained the same in 2008. The ratio of the number of girls to the number of boys in 2009 was the same as the ratio in 2007.
How many pupils were there in 2009?

Hi

This question has been discussed before.

You may wish to draw a MD.

2007
Girls ------9units+90
Boys ------9units

2008
Girls ------6units+60
Boys ------14units (increased by 5/9)

20 units +60 ------660
1 unit -------30

a)In 2007, boys --------9*30 -----270 and girls --------360
Therefore 270/630 --------3/7

In 2008, boys ------ 14*30 ------ 420

In 2007 Girls: Boys ------- 360:270 ------4:3

In 2009 Boys ------420, Girls -----560

Therefore total number ------- (420+560) -------980

Best wishes

[fightingmom]

:thankyou: , tianzhu !

[elkniwt]

Dear tianzhu,


Thank you very much!!! Thank you!!

Regards.

tianzhu:

elkniwt:

Hello,

Need help in this qn from Henry Park 2011 Prelim :

http://i48.tinypic.com/2i7qozm.jpg\">

Thanks!!

Hi

Please refer to earlier discussion.

Best wishes

http://www.kiasuparents.com/kiasu/forum/viewtopic.php&f=69&t=280&p=778481

But I think, there are added shaded portions inside the image as this is the duplicated set.

I’d go for

½ of square (12*12) – ½ of semicircle (r6) ------- 15.45

Area of 1 quadrant (r6) -------- 28.27

Total area ------ 43.72 (15.45 + 28.27)

Best wishes