Q&A - PSLE Math

[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.

[Vanilla Cake]

Susan has some vanilla and chocolate sweets in her bag. If she adds 20 vanilla sweets into the bag, the percentage of vanilla sweets in the bag becomes 40%. If she adds 30 chocolate sweets, there will be 70% of chocolate sweets in the bag. How many vanilla and chocolate sweets does she have? [5 marks][Answer given: 64 vanilla sweets and 126 chocolate sweets]


Thank you for your time and effort. I appreciate your help as I think that the answer given is incorrect.

My answers are : Vanilla sweets: 72 and Chocolate sweets: 138
Took me about 10 min plus using 2 different methods to crack this problem sum.Pls help to clarify if I am correct or the given answer is correct.

[tianzhu]

Vanilla Cake:

My answers are : Vanilla sweets: 72 and Chocolate sweets: 138
Took me about 10 min plus using 2 different methods to crack this problem sum.Pls help to clarify if I am correct or the given answer is correct.

Hi VC

You're are correct.

Best wishes

[Vanilla Cake]

tianzhu:

Vanilla Cake:

My answers are : Vanilla sweets: 72 and Chocolate sweets: 138

Took me about 10 min plus using 2 different methods to crack this problem sum.Pls help to clarify if I am correct or the given answer is correct.

Hi VC

You're are correct.

Best wishes

Thks, Uncle Tianzhu for your confirmation.Now, I am working on these 10 Maths papers from 2010 P6 Prelim. Definitely, the level of P6/PSLE Maths is getting higher nowadays than my good old days when I took PSLE Maths 2008.

[kancheongmum]

Hi Tianzhu

Ha ha did not realize the time when I worked on the solution. I just got the papers yesterday and looking through them first before I let ds try. You are right, is definitely worth looking through these papers. Spent only $35 for 3 subjects. DH out of job for 6 mths already cannot afford tuition. Looking at how much tuition centre charged for intensive psle revision this is only a small fraction. I had paid a private maths tutor $100/h before but stop after 4 mths as it did not work well. I am still the best and free tutor. Big thank to all the helpful souls like you, Dharma and others. So willing the help anytime without the $$$$ attached.

Here is another problem:

In a group of 36 students, the number of students who like sushi is thrice the number of students who like nuggets. If 2 students like neither sushi nor nuggets and 6 students like both, how many students like nuggets? (ans 10)