Q&A - PSLE Math

[Tang]

Dharma:

fxchow:

hi tianzhu,


Wish you have a nice weekend too!

BTW, do you have any tips to handle P6 math? i really lost.

In fact, my girl likes math and scored good results in P4 & P5.
But this year I can see that she is facing difficulty.
She confuses with the ratio, fraction & percentage....now add on speed, circle.....

Perhaps someone can recommend a \"specialist\" math tutor or tuition center in West to me. TIA

Dear fxchow,

I understand your worry for your child but if she has handled her P4 and P5 work well she will have a strong foundation already. Ratio, fraction and percentage are P5 topics and are carried forward to P6 but at a higher level. Only new topics in P6 are speed and circles.

Regarding ratio, fraction and percentage....they are all related and are the same things expressed differently.

I notice most parents produce beautiful solutions to problems sums using the model method. For some reason or another, I prefer the units method as I find it a faster method.

If you notice most problem sums under fractions and percentages can be expressed in ratio form.

You child needs to be able to quickly express percentages in form of fractions. Once you know the fraction, express it in ratio to solve the problem. Ratios are very useful and will help your child ..... when we draw models to express fractions or percentages, we are expressing the ratio of two or more objects in a pictorial form.

Once you it is in ratio form...get her to read the question carefully and move on. The questions asked are normally very standard....

Important to get the basics right ...

For speed, 2 main type of qns ...meeting and catching up. Your child need to be able to handle these 2 types. Go thru school worksheets/textbook for the process.

Ratio is important when comes to speed qns.

Need to understand,
1.For a fixed distance, the ratio of the speed of 2 vehicles will be inversely proportional to ratio of the time taken by the 2 vehicles.

2. For a fixed time, ratio of speed of 2 vehicles is same as the ratio of the distance travelled by the 2 vehicles.

For circles, must know area and perimeter of circle. But problem is normally ...the diagram given is more complicated than a simple circle. Your child need to have clear mind on how to manipulate/shift/slide the figures/diagram....she needs good sleep before the exam to do this.

As regards to Maths tuition...you may wish to try Maths Hub at Bukit Batok ..my older daughter went there for her SMOP training 2~3 years ago. They also do PSLE maths and have different classes for different learning abilities.

Just get you child to understand how fractions and percentages are expressed in ratios ....guess things will not be so confusing anymore.

Fractions and Percentages can be converted to Whole Numbers.

Eg 1) A is 4/5 of B.
A -- 4 units
B -- 5 units

2) A is 40% of B
A -- 4 units
B -- 10 units
or simplify further into
A -- 2 units
B -- 5 units

3) Total number of apples and oranges is 100. After 2/3 of apples and 1/4 oranges are removed, the number apples and apples left is 40. [Numbers may not make sense]

3 Au + 4 Ou = 100
1 Au + 3 Ou = 40
Then solve.
Just remember that total number of apples is 3 Au and total number of oranges is 4 Ou.

Good Luck!

[tianzhu]

Drdj:

[Moderator's note: Topics merged.]


This is from Nanyang SA1 2008.
Could someone help me to solve this sum without guess-and-check method? (this was the worked solution)

Wayne has five more 50 cent coins than 20 cent coins. After he used eight 50 cent coins, the value of 50 cent conis is $1.50 more than the value of 20 cent coins. How many coins did he have at first?

Thanks in advance.

This question is from Nanyang P6 SA1 2008.
http://wendykoh.com/08/primary6-nanyangsa1-maths.pdf

We need Chiefkiasu's help to move it to the right thread.

[Tang]

Tang:

tianzhu:

[quote=\"Drdj\"][Moderator's note: Topics merged.]


This is from Nanyang SA1 2008.
Could someone help me to solve this sum without guess-and-check method? (this was the worked solution)

Wayne has five more 50 cent coins than 20 cent coins. After he used eight 50 cent coins, the value of 50 cent conis is $1.50 more than the value of 20 cent coins. How many coins did he have at first?

Thanks in advance.

This question is from Nanyang P6 SA1 2008.
http://wendykoh.com/08/primary6-nanyangsa1-maths.pdf

We need Chiefkiasu's help to move it to the right thread.

[/quote]8 - 5 = 3. [Remove 5, so number of 50-cent and 20-cent coins supposed to be the same. But since he spent 8 50-cent coins, he now has 3 50-cent coins less.]
3 50¢ = 150¢.
150 + 150 = 300 ¢ (more). [Putting back the 3 50-cent coins, the amount of 50-cent coins will be 300 cents more than the amount of 20-cent coins.]
50 - 20 = 30¢ (more) [The difference between 1 50-cent coin and 1 20-cent coin]
300 ÷ 30 = 10 20¢ coins. [Total difference / One difference gives you the number of 20-cent coins. To get the number of 50-cent coins, you will need to 5.]

To solve such problem sum, always try to make the number of coins the same.

[Tang]

kiasiparent:

Vanilla Cake:

[quote=\"_jas_\"]Hi help needed for these questions! ASAP pls as my child has an exam coming up!!


1) A bus left town A for town B at a speed of 45km/h. At the same time, a van left Town B for Town A at the speed of 55km/h. Both vehicles travelled along the same road. how far apart were they 1 hour before they met (ans:100km)

2) At 09 00, a van left Town P for Town Q. After some time, a car left Town Q for Town P. The two vehicles met at 11 30. The ratio of the average speed of the van to the average speed of the car is 3:5.
a) What time did the car leave town Q (ans:10 00)
b) If the distance between town P and Town Q is 150 km, calculate the average speed of the van. (ans:30km/h)

3) The ratio of the amount of water in Bottle A to the amount of water in Bottle B was 2:1. After 60ml of water was pured into Bottle A and 150ml was poured out of bottle B, the ratio became 4:1.
What was the amount of water in bottle A at first? (Ans:660)

TIA!

tianzhu:

As for Q2, you may wish to check your question again.Is there any missing information such as meeting at midway?

For Info:
Q1 - Raffles Girls' Primary School - P6 Maths SA1 (2008) - Q33
Q2 - Raffles Girls' Primary School - P6 Maths SA1 (2008) - Q48
Q3 - Raffles Girls' Primary School - P6 Maths SA1 (2008) - Q42

Q2 as appeared in the paper http://www.wendykoh.com/08/primary6-rgssa1-maths.pdfType password as \"abc123\" and go to page 24 for Q48.
At 09 00, a van left Town P for Town Q. After some time, a car left Town Q for Town P. The two vehicles met midway at 11 30. The ratio of the average speed of the van to the average speed of the car is 3:5.
a) What time did the car leave town Q?
b) If the distance between town P and Town Q is 150 km, calculate the average speed of the van.

Q2 was a maths olympiad question last time. Now it has become a rather common question in maths syllabus question.

Speed Van: Car = 3:5
Time Van: Car = 5units :3 units

Since they travelled the same distance(midway), the time taken by the van will be 5 units and the car will be 3 units respectively.

11.30 - 9.00= 2 hours 30mins

5 units = 2 hours 30 mins
1 unit = 30mins
3 units = 1 hour 30 mins

So the car leave town Q at 11.30 - 1.30 = 10.00am

(b) 150 / 2 = 75
75 / 2.5hours = 75 x 2/5 = 30 km/h[/quote]So the car leave town Q at 11.30 - 1.30 = 10.00am

Please note that 11.30 - 1.30 = 10.00 am will be marked wrong because pupils are not supposed to mix Time (11.30 am) with Duration (1h 30 min) to derive Time (10.00 am). They are supposed to use Timeline to work out the answer.

[Drdj]

[Moderator's note: Topics merged.]


Hi all,

Could you help me to solve this sum? The answer is 12.5 cm2.
Greatly appreciated.


http://www.postimage.org/image.php?v=PqTgCZ9

[jedamum]

Drdj,

2nd reminder - please post in the existing http://www.kiasuparents.com/kiasu/forum/viewtopic.php?t=280&start=0

go to the relevant thread and click postreply for posting new questions in the existing thread.

[Drdj]

My abject apologies....for the inconvenience caused

jedamum:

Drdj,
2nd reminder - please post in the existing http://www.kiasuparents.com/kiasu/forum/viewtopic.php?t=280&start=0

go to the relevant thread and click postreply for posting new questions in the existing thread.

[David Koriadi]

Drdj:

Hi all,

Could you help me to solve this sum? The answer is 12.5 cm2.
Greatly appreciated.
http://www.postimage.org/image.php?v=PqTgCZ9

Pls refer to this http://3.bp.blogspot.com/_NGNaLTzN5_U/SQxOIlT-arI/AAAAAAAAA8A/AJ4y75elZiI/s1600-h/MathsCirclesQ001a.JPG posted by Uncle Observer for explanation and answer.

[kiasiparent]

Drdj:

Hi all,


Could you help me to solve this sum? The answer is 12.5 cm2.
Greatly appreciated.


http://www.postimage.org/image.php?v=PqTgCZ9

If you use pythagoras' theorem, the triangle will no longer be 33cm2 but just an approximation.

[Drdj]

Hi, I've tried very hard, but I can't seem to understand Uncle Observer's answer....any simpler method out there, or would someone be kind enough to explain his method?

Thanks

David Koriadi:

Drdj:

Hi all,
Could you help me to solve this sum? The answer is 12.5 cm2.
Greatly appreciated.
http://www.postimage.org/image.php?v=PqTgCZ9

Pls refer to this http://3.bp.blogspot.com/_NGNaLTzN5_U/SQxOIlT-arI/AAAAAAAAA8A/AJ4y75elZiI/s1600-h/MathsCirclesQ001a.JPG posted by Uncle Observer for explanation and answer.