Q&A - PSLE Math

[kiasiparent]

Algebra are allowed in PSLE.


In fact, last year PSLE requires a lot on the use of algebra to answer a few questions. Other than using algebra, you can also use units and parts but that’s actually algebra in disguise.

Other than that, You probably have to use guess and check.

[Priskhipo]

enoawng:

Dharma:

Hi Andrew,


mathsparks is right.

Mr Ng bought three times as many badges as toy cars and spent $144 in total. He spent $84 more on toy cars than on badges. Given that a toy car cost $10.4 more than a badge, what was the cost of the bagde?

Ok can anyone confirmed that this method below is allowed and the child will be awarded full marks?

Let N be the number of cars and B the cost of badge

3NB + N(B+10.4) = 144


N(B+10.4) -3NB = 84

Solving above
6NB = 144-84=60
NB=10

From 2nd statement
NB+10.4N-3NB = 84
10.4N= 84+20= 104
N=10; B=$1

Also if we don't use Dharma's method or the algebric method, is there a model method?

Many thanks in advanced.

Here is the model method:


http://www.postimage.org/

[enoawng]

Priskhipo:

[


Here is the model method:


http://www.postimage.org/

Thanks. But I think the purple part should be cost of badges and the cost of cars should be purple + blue part, right?

But just wondering if the model method is easier for the boys/girls during examination or is it better to use algebra approach.

Anyone parents has any good advice or experiences?

[Dharma]

tianzhu:

Maybe, I am a much laid back father who just wants my kid to learn sufficient knowledge without subjecting him to additional stress.

Tianzhu,

You contribution to this forum is an encouragement to many other parents to share their knowledge, discuss and solve problems ...all for the sake of our kids. You're an inspiration to others and surely not laid back.

[youngmum]

Hi, can help me solve these 2 questions pls. They are in my boy homework. Thanks.



Q1

When Mrs Lee was 40 years old, her son was twice her daughter’s age. Mrs Lee will be twice her son’s age when her daughter is 28 years old. How old will Mrs Lee be when her daughter is 20 years old? (56 years old)

Q2
At 7am, Car A left Town X for Town Y while Car B left Town Y for Town X. At 3pm, the two cars passed each other. 5 hours later, Car A reached Town Y but Car B was still 150km away from Town X. Find the distance between Town X and Town Y.

[3greatkids]

Hi youngmum, for qn1 u need to use the guess and check method.




http://www.postimage.org/

Since daughter and mum age difference is 40-4=36, thus when daughter is 20, mum is 20+36=56

[3greatkids]

qn 2


http://www.postimage.org/image.php?v=Pq1m9OmA

*please take note that the last sentence should be \"we take speed x time\" and not distance... paiseh paiseh

[pikachu]

Qn 1


When Mrs Lee was 40 years old
Son : 2 units
Daughter : 1 unit

Some y years later when daughter was 28 years old
Son : 2 units + y
Daughter : 1 unit + y = 28
Mrs Lee : 2 units + y + 2 units + y

2 unit = 40 - 28
1 unit = 6
y = 22
When daughter was 28 years old, Mrs Lee was 40 + 22 = 62.
8 years ago, she was 62 - 8 = 54 years old.

[Dharma]

youngmum:

Hi, can help me solve these 2 questions pls. They are in my boy homework. Thanks.



Q1

When Mrs Lee was 40 years old, her son was twice her daughter's age. Mrs Lee will be twice her son's age when her daughter is 28 years old. How old will Mrs Lee be when her daughter is 20 years old? (56 years old)

Hope this helps
http://www.postimage.org/

[N3SKiasu]

tianzhu:

Hi

I don't get what you meant by some of the picture/slides posted (by Dharma) didn't show up.

But, if you want to copy his slides on document(say using MS Word), just place mouse's arrow over selected slide, do a right click and select copy.Then paste into your Word document.

Hope I've addressed your concern.

Best Wishes

Thanks Tianzhu for your reply.

I managed to find out why I could not see the pictures posted by all earlier. It was due to the K9 web protection software (I found this software via recomm in KSP), it stopped some images web page that might contain inappropraite images for children. It is fine now after I have allowed assess to this imaging web page. Kind of strict from this software but it works well for children!

Btw, I salute your efforts in taking the time to solve so many problem sums and science questions with your child...I have been trying to follow the speed this topic grow but couldn't catch up...while your wife may have some comments...I wld rather my husband to draw model than watching his TV prog all the times. :x Perhaps he prefers to draw the model of the lady figure in the show than the complicated Maths model