Q&A - P3 Math

[jedamum]

mods,

pls merge.
http://www.kiasuparents.com/kiasu/forum/viewtopic.php?t=149&start=0
TQ.

[tianzhu]

Hi

Q2 touches on averages.
Is averages covered in P4 Maths?

[bwpj2000]

I think averages is covered in P4 Math, I'm not very sure. :?

[Vanilla Cake]

bwpj2000:

Need help with these questions from my son's P4 homework:


Q1. Edward has $40 more than Fariq. If Edward gives 1/5 of his money to Fariq, Fariq will have 7/8 as much money as Edward. How much money do they have altogether?

Q2. When Janice bought some files, the average cost was $4. After she bought one more file at $16, the average cost was $7. How many files did she buy at first?

Q3. Alex's monthly salary is $80 more than Bernard's monthly salary. Every month, they spend $950 each and save the rest of their money. After a few months, Alex saved $2805 while Bernard saved $1605.
(a) How many months did Alex take to save $2805?
(b) What is the total amount of money Alex and Bernard will earn in a month?

Responses are very much appreciated.

Hi bwpj2000,
I don't think that these sums are for P4 level as they are most likely to be P5 Maths. Anyway, hope the below solutions help.

A1.
Edward -> unit + 40
Fariq -> unit

4/5 x (unit+40) = 4unit/5 + 32 = 0.8unit + 32
(0.8unit +32)/(1.2unit +8 ) = 8/7
8(1.2unit +8 ) = 7(0.8unit + 32)
9.6 unit + 64 = 5.6 unit + 224
4 units = 160
1 unit = 40

Total amount-> $(40x2) + 40 = $120

A2
16-7 = 9 (Extra from one more file)
7-4 = 3 (Increase in average ie each file increased by 3)

Number of files that Janice bought at first = 9/3 = 3

A3
(a) Number of months-> (2805-1605)/80 = 15

(b) Amount that Alex earned in 1 month = (2805/15)+950 = $1137
Total amount of money that Alex and Bernard earned in a month = $1137 + $(1137-80) = $2194

[elkniwt]

Hi,


I was going thr' this paper with my P3 girl. Need help in this qn. Thanks

Catholic High 2007 CA2 Q40.

http://www.postimage.org/image.php?v=Ts2ds4FJ

[watmekiasu]

I've deleted my answer since it is not right. Do not wish anyone to waste time figuring out my method. :lol:

[elkniwt]

watmekiasu:

Elkniwt


Hope this is correct -

1st - 3/8 + 3/8 = 6/8 = 3/4
2nd - 1/12 + 1/12 = 2/12 = 1/6
3rd - 1/3 + 1/6 = 3/6 = 1/3

so, the answer is 1/6

The ans given by the ans sheet is 2/9. I couldn't get it.

[qic]

The answer is as follows:


3/8-1/8+3/8/+1/8=6/8=3/4
4/12-1/3+1/12+1/12=2/12=1/6
3/9-1/3+?+1/9=1/3=3/9

?=2/9

[elkniwt]

qic:

The answer is as follows:


3/8-1/8+3/8/+1/8=6/8=3/4
4/12-1/3+1/12+1/12=2/12=1/6
3/9-1/3+?+1/9=1/3=3/9

?=2/9

Wow!! thanks!!! The pattern is quite unusual. Not easy to see the pattern even after I know the ans. Wondering how am I going to teach my dd to attempt it ?? Thanks again.

[Devnahouse]

Can help...... pls.. :?


Anglo Chinese P3 SA2 2007:
Mother has some money to buy beef. She will have $15 left if she buys 3kg of beef. However, she will need $3 more if she wants to buy 4kg of beef instead. How much money does Mother have?

Answer is $69? How?