Q&A - PSLE Math

[atutor2001]

Vanilla Cake:

Hi Uncle Tianzhu / Uncle Dharma,


Sorry to bother both of you. Pls refer to this http://psle2010a.blogspot.com/2010/09/volume-p6-2010-sa2-hhk-p2-q-18.html for the unusual volume question from SHHK P6 Prelim 2010 Paper 2 Q18 [5 marks]. Could you pls paste and post this question c/w diagram in KSP forum to share among readers and offer your views in addition to Uncle Observer's solution. I had tried to post this diagram but the size was too big. How do you control the size of the image/diagram that you want to post here?
Thanks.

Hi Vanilla cake

During my kids' time, they were taught to remember this as the \"candle question\" because the question was given as 2 candles of different lengths being burnt at different time.

The solution given was based on algebra - kind of difficult for P6 to digest.

Remembered teaching my kids to use model which is easier. The height of each tank is first divided into parts, equal to the \"number of half-hour\" Then by comparing the portion after 11 pm (being equal in height) we can sub-divide the units into equal size. We will then get 4 units = 5cm. The height of tank A will be 36 units, which will then work out to be 45cm.

Sorry don't know how to draw and post the proper model.

[moomoo7368]

Hi vanilla cake, thanks for your links regarding 2010 prelim papers!

[kancheongmum]

Vanilla Cake:

Hi Uncle Tianzhu / Uncle Dharma,


Sorry to bother both of you. Pls refer to this http://psle2010a.blogspot.com/2010/09/volume-p6-2010-sa2-hhk-p2-q-18.html for the unusual volume question from SHHK P6 Prelim 2010 Paper 2 Q18 [5 marks]. Could you pls paste and post this question c/w diagram in KSP forum to share among readers and offer your views in addition to Uncle Observer's solution. I had tried to post this diagram but the size was too big. How do you control the size of the image/diagram that you want to post here?
Thanks.

Hi Vanilla Cake

Uncle Observer's solution is very difficult for my ds to understand and I find it the same too. So I used the 'candle method' which Uncle Observer had posted before. If I am not wrong is the equal fraction method. Let me try and I hope is not too complicated to understand. Tianzhu and Dharma pls give your view and correct me if I am wrong. Tks

Tank A emptied in 6 hrs --- 1 hour emptied 1/6 tank
Tank B emptied in 4 hrs --- 1 hour emptied 1/4 tank
Tank A in 4 hrs and Tank B in 2.5 hrs will reach the same height.
That means remaining tank to emptied
Tank A === 1 - (1/6 x 4) --- 1/3 tank
Tank B === 1 - (1/4 x 2.5) --- 3/8 tank

1/3 of height of Tank A is equal to 3/8 of height of Tank B
1/3 ---- 3/9

Height of Tank A 9u
Height of Tank B 8u

9u - 8u = 1u --- 5cm
Height of Tank A is 9 x 5 = 45cm

[Vanilla Cake]

kancheongmum:

Hi Vanilla Cake


Uncle Observer's solution is very difficult for my ds to understand and I find it the same too. So I used the 'candle method' which Uncle Observer had posted before. If I am not wrong is the equal fraction method. Let me try and I hope is not too complicated to understand. Tianzhu and Dharma pls give your view and correct me if I am wrong. Tks

Tank A emptied in 6 hrs --- 1 hour emptied 1/6 tank
Tank B emptied in 4 hrs --- 1 hour emptied 1/4 tank
Tank A in 4 hrs and Tank B in 2.5 hrs will reach the same height.
That means remaining tank to emptied
Tank A === 1 - (1/6 x 4) --- 1/3 tank
Tank B === 1 - (1/4 x 2.5) --- 3/8 tank

1/3 of height of Tank A is equal to 3/8 of height of Tank B
1/3 ---- 3/9

Height of Tank A 9u
Height of Tank B 8u

9u - 8u = 1u --- 5cm
Height of Tank A is 9 x 5 = 45cm

Hi kancheongmum,

Yes, you are right as it took me about 15 minutes plus to understand Uncle Observer's solution considering the fact that I am a year 2 (Sec 2) student. :oops:
Refer to http://www.kiasuparents.com/kiasu/forum/viewtopic.php?t=6373&postdays=0&postorder=asc&start=2420.
Another similar question also came out in the River Valley Primary School P6 Prelim Maths 2010 Paper 2 Q17 [5 marks] :

Candle A and candle B are of the same length. Candle A, which is broader, can burn for 5 h while Candle B, the thinner candle, can burn for 4 h. If both candles are lighted at the same time, how long does it take for Candle A to be twice as long as Candle B?
Answer : 3⅓ hours

Off-topic. The newly released package of 10 schools per subject for 2010 P6 Prelim top papers comes at a price tag of $40 for 4 subjects.
4 subjects x 10 schools = 40 papers
$40 ÷ 40 = $1 per paper

Interesting number and pls don't get me wrong. I am not trying to promote these top papers. Just a casual remark to ease the PSLE 2010's tension and pressure.

[Dharma]

kancheongmum:

Vanilla Cake:

Hi Uncle Tianzhu / Uncle Dharma,


Sorry to bother both of you. Pls refer to this http://psle2010a.blogspot.com/2010/09/volume-p6-2010-sa2-hhk-p2-q-18.html for the unusual volume question from SHHK P6 Prelim 2010 Paper 2 Q18 [5 marks]. Could you pls paste and post this question c/w diagram in KSP forum to share among readers and offer your views in addition to Uncle Observer's solution. I had tried to post this diagram but the size was too big. How do you control the size of the image/diagram that you want to post here?
Thanks.

Hi Vanilla Cake

Uncle Observer's solution is very difficult for my ds to understand and I find it the same too. So I used the 'candle method' which Uncle Observer had posted before. If I am not wrong is the equal fraction method. Let me try and I hope is not too complicated to understand. Tianzhu and Dharma pls give your view and correct me if I am wrong. Tks

Tank A emptied in 6 hrs --- 1 hour emptied 1/6 tank
Tank B emptied in 4 hrs --- 1 hour emptied 1/4 tank
Tank A in 4 hrs and Tank B in 2.5 hrs will reach the same height.
That means remaining tank to emptied
Tank A === 1 - (1/6 x 4) --- 1/3 tank
Tank B === 1 - (1/4 x 2.5) --- 3/8 tank

1/3 of height of Tank A is equal to 3/8 of height of Tank B
1/3 ---- 3/9

Height of Tank A 9u
Height of Tank B 8u

9u - 8u = 1u --- 5cm
Height of Tank A is 9 x 5 = 45cm

Hi kancheongmum,

Your solution is clear and correct.

[tianzhu]

Hi VC and kancheongmum


Good Morning

Hope this helps.

This question touches on the concept of equal fractions. It is quite similar to the candle solution which I posted earlier in this thread.

A good way to solve such questions is to use MD.

Best wishes

http://farm5.static.flickr.com/4133/4975546078_eaed16dcca_b.jpg\">

[tianzhu]

Hi kancheongmum


Your solution is correct.

You are certainly working hard for your kid’s exam, solving Maths question @ 2.39am

Best wishes

[tianzhu]

Vanilla Cake:

I had tried to post this diagram but the size was too big. How do you control the size of the image/diagram that you want to post here?.

Hi VC

For Flickr, you can select the sizes,small,medium,large.
I am not familiar with the other storage media.

Best wishes

[abc_parent]

Hi all


I am not sure about Q12, 13, 14 and Q18.

Q12) Tank P was filled with water as shown in the diagram (pls help with this if you have the diagram). Water was then poured from Tank P to Tank Q until the height of the water level in Tank P became twice that of the water level in Tank Q. Find the volume of water in Tank Q. Given your answers in litres.

Q13) A van travelled from Town A to Town B at an average speed of 55 km/h. A car started its journey from Town B to Town A at the same time as the van travelling at an average speed of 90km/h. The two vehicles passed each other 70 km from the middle of the whole journey. Find the distance between the two towns.

Q14) Cinema admission tickets for children were priced at $8 each. There were 20 more boys than girls in the cinema for the first movie. For the second movie, the number of boys decreased by 10% but the number of girls increased by 5%. If there were 408 children at the second movie, how much money was collected from the sales of admission tickets for the first movie?

Q18) (this question also has a diagram, please help if you have it) The shaded figure below is formed by a semi circle and quarter circle. It lies within rectangle PQRS in which RU = 1cm, UQ = 2 cm, PT = 3 cm.
(a) Find the perimeter of the shaded region. Give your answer in terms of pi.
(b) Find the area of the shaded region. Give your answer correct to 2 decimal places.[/b]

[Vanilla Cake]

abc_parent:

Hi all


I am not sure about Q12, 13, 14 and Q18.

Q12) Tank P was filled with water as shown in the diagram (pls help with this if you have the diagram). Water was then poured from Tank P to Tank Q until the height of the water level in Tank P became twice that of the water level in Tank Q. Find the volume of water in Tank Q. Given your answers in litres.

Q13) A van travelled from Town A to Town B at an average speed of 55 km/h. A car started its journey from Town B to Town A at the same time as the van travelling at an average speed of 90km/h. The two vehicles passed each other 70 km from the middle of the whole journey. Find the distance between the two towns.

Q14) Cinema admission tickets for children were priced at $8 each. There were 20 more boys than girls in the cinema for the first movie. For the second movie, the number of boys decreased by 10% but the number of girls increased by 5%. If there were 408 children at the second movie, how much money was collected from the sales of admission tickets for the first movie?

Q18) (this question also has a diagram, please help if you have it) The shaded figure below is formed by a semi circle and quarter circle. It lies within rectangle PQRS in which RU = 1cm, UQ = 2 cm, PT = 3 cm.
(a) Find the perimeter of the shaded region. Give your answer in terms of pi.
(b) Find the area of the shaded region. Give your answer correct to 2 decimal places.[/b]

Hi abc_parent,
Here's the online version of the http://www.orlesson.org/orp/09Ma/2009-P6-Math-SA2-HenryPark.pdf.Sorry, I am busy working on the 2010 P6 Prelim Maths exam papers and pls wait for other KSP members to help.

You wish wish to http://prischoolmaths.blogspot.com/2009/09/henry-park-speed.html for your Q13 on speed.http://4.bp.blogspot.com/_NGNaLTzN5_U/SrTHBF0N2oI/AAAAAAAADws/wAhKWR0oCIk/s1600-h/Maths0609SA2P2HPCicrleQ18A.JPG for your Q18.I think it's good if you can type out the given answer for the question as it will save time for the potential problem solvers. Just my 2 cents.