2011 PSLE Discussions and Strategy

[Pen88n]

Thanks, Vanilla Cake. Really appreciate you providing answers for Nanhua and MGS

[Pen88n]

Vanilla Cake:

Pen88n:

I am looking for Nanhua and MGS Maths paper 2 answers. Would appreciate if anyone who has it can post. Thanks

Hi Pen88n,

Answers for Nan Hua Pri Sch 2011 P6 Prelim Maths exam paper set on 24 August 2011:

Paper 1
Q1. 4
Q2. 3
Q3. 4
Q4. 3
Q5. 2
Q6. 2
Q7, 4
Q8. 4
Q9. 1
Q10. 1
Q11. 3
Q12. 3
Q13. 1
Q14. 1
Q15. 2
Q16. 2/5, 1/2, 2/3, 3/4
Q17. 1.375
Q18. 200%
Q19. 9:4
Q20. 10 people
Q21. 16 cm
Q22. 36
Q23. 1/2
Q24. 3:5
Q25. 81
Q26. 2 cm
Q27 25 m
Q28. Count from left to right and top to bottom: 1st column,5 row and 5th column, 3rd row.
Q29. 44 cm
Q30. 75 degree

Paper 2
Q1. (2x+14) years
Q2. 8 pupils
Q3. 34 circles
Q4. 24 cm
Q5. 0.65
Q6. Length of AC = 12.4 cm
Q7. 12 pears
Q8. 5 yellow marbles
Q9. $ 440
Q10. 15 seconds
Q11. 44 cm
Q12. (a) 65 degree (b) 20 degree
Q13. 20 boys
Q14. 39 each of $8-seats
Q15. 14 00
Q16. (a) 54 litres (b) 20 cm
Q17. (a) 16, 11, 32 (b) 400 (c) 34 (d) 1250
Q18. (a) $108 (b) $96

Vanilla Cake,

DS has only done paper 2 due to limited time.

There are 2 questions whereby he has different answers compared with yours and I've checked through and his answer seems ok. Below are the 2 questions:

Q13) His ans: 34 boys
Adult: Boys : Girls => 16 : 3 : 1
Diff between boys and girls: 3u - 1u = 36 => u = 18
Adult + Girls: 17u = 18 x 17 = 306
90% are adults and girls, 10% boys: 306 / 9 = 34 boys

Q16(b) His ans: 7.5cm
After 20 mins, 6l of water drained
2 container base is 500+300 cm sq, so height will be: 6l / 800 cm sq = 7.5cm

Hope to share learning. Once again, thanks for sharing.

[Pen88n]

Vanilla Cake:

Pen88n:

I am looking for Nanhua and MGS Maths paper 2 answers. Would appreciate if anyone who has it can post. Thanks

Answers for MGS 2011 P6 Prelim Maths exam paper set on 24 August 2011:

Paper 1
Q1. 2
Q2. 4
Q3. 2
Q4. 1
Q5. 3
Q6. 4
Q7. 3
Q8. 4
Q9. 4
Q10. 3
Q11. 3
Q12. 1
Q13. 4
Q14. 3
Q15. 3
Q16. 31
Q17. 4/9, 4/15, 2/17
Q18. 15000.02 m
Q19. 4 each of fifty-cent coins
Q20. 395 ml
Q21. 5 min
Q22. 30:7:15
Q23. 4 bottles
Q24. Unable to solve
Q25. Rhombus
Q26. 25 July
Q27. $ 7
Q28. 14 cm
Q29. 500 cm2
Q30. $20

Paper 2
Q1. 5 questions
Q2. 78 cm2
Q3. 12 min 48 s
Q4. H and O
Q5. $10.60
Q6. 35 years old
Q7. 3 months
Q8. (a) (12d+150) kg (b) 70.62 kg (correct to 2 decimal places)
Q9. 95 fiction books
Q10. 49.16 kg (correct to 2 decimal places)
Q11. 63 cm2
Q12. Unable to solve due to incomplete information given.
Q13. (a) 16 cm (b) 19.28 cm (correct to 2 decimal places)
Q14. Unable to solve due to incomplete information given.
Q15. (a) 48 picture cards (b) 72 more picture cards
Q16. (a) 99 degree (b) 9 degree
Q17. (a) 21 children (b) 28.6%
Q18. 40 stamps

As usual, DS only attempted paper 2. There is a question with a different answer:
Q10) His ans: 47.8kg
Total of 3 boys: 72.6kg x 3 = 217.8kg
C:B:A = 8:10:15
Carl's weight without considering defect: 8/33 x 217.8kg = 52.8kg
Consider defective: 52.8kg - 5kg = 47.8kg

Note: the defective scale is affecting the 3 boys each 5kg difference. If you minus off 15kg difference from the total, based on the ratio of the boys' weight, it will be inaccurate as it is thus not the same 5kg difference for each boy.

Hope this clarifies the matter. Once again, thanks for sharing the answer. It certainly helps make my marking job much easier as I can zoom into the \"inaccurancies\" in his answers right away!

[Pen88n]

Vanilla Cake,

Btw, do you happen to have the answer to MW tuition Maths paper from the unknown school? Again, DS has only attempted paper 2, and I'm looking for an easy way out for marking instead of doing all the sums again Thanks in advance.

[P6ians]

Hi

Is it possible to find Nanyang math. Prelim 2011 in any website?
Pls. Help. thank you.

[Vanilla Cake]

Vanilla Cake:

Paper 2
Q13. 20 boys
Q16. (a) 54 litres (b) 20 cm

Pen88n:

There are 2 questions whereby he has different answers compared with yours and I've checked through and his answer seems ok. Below are the 2 questions:

Q13) His ans: 34 boys
Adult: Boys : Girls => 16 : 3 : 1
Diff between boys and girls: 3u - 1u = 36 => u = 18
Adult + Girls: 17u = 18 x 17 = 306
90% are adults and girls, 10% boys: 306 / 9 = 34 boys

Q16(b) His ans: 7.5cm
After 20 mins, 6l of water drained
2 container base is 500+300 cm sq, so height will be: 6l / 800 cm sq = 7.5cm

Here's are the workings done by younger sister for the above 2 questions:

Q13
Before
Adults -> 80% ie 0.8u
Boys -> 75/100x20% = 15% ie 0.15u
Girls -> u-0.8u-0.15u = 0.05u

After
Adults -> 0.8u (No change)
Girls -> 0.05u (No change)

Adults+Girls -> 0.8u+0.05u = 0.85u -> 90%
Boys -> 10% = 0.85u/90x10 = 17u/180

Difference between boys and girls in the beginning -> 0.15u-0.05u = 0.1u
0.1u -> 36
u = 360

Boys (before) - Boys (after) = 0.15u - 17u/180 = u/18 (Boys that left)
u/18 = 360/18 = 20

Number of boys that left the hall = 20

Q16(a)
800-500 = 300
(40x50x30)-(300x20) = 54000 cm3 = 54 litres
Amount of water left in the tank after 20 minutes = 54 litres

Q16 (b)
800x20 = 16000
Assume height of the water level to be u,
(ux500)+(ux300) = 16000
u = 20 cm
Height of the water level in the 2 containers after 20 minutes = 20 cm

Alternative solution for Q16 (b) done by http://www.kiasuparents.com/kiasu/forum/viewtopic.php?f=69&t=280&start=4450 is over here.

Pen88n:

Hope to share learning. Once again, thanks for sharing.

You are most welcome!

[Vanilla Cake]

Vanilla Cake:

Paper 2

Q10. 49.16 kg (correct to 2 decimal places)

Pen88n:

As usual, DS only attempted paper 2. There is a question with a different answer:
Q10) His ans: 47.8kg
Total of 3 boys: 72.6kg x 3 = 217.8kg
C:B:A = 8:10:15
Carl's weight without considering defect: 8/33 x 217.8kg = 52.8kg
Consider defective: 52.8kg - 5kg = 47.8kg

Note: the defective scale is affecting the 3 boys each 5kg difference. If you minus off 15kg difference from the total, based on the ratio of the boys' weight, it will be inaccurate as it is thus not the same 5kg difference for each boy.

Q10 is a controversial question and the answer depends on how you interpret it. In fact, I have posted it over http://www.kiasuparents.com/kiasu/forum/viewtopic.php?f=69&t=280&start=4320 and hope to get some replies.

My younger sister also did the way that your DS did to get 47.8 kg.

72.6x3 = 217.8
B : A
2 : 3

B : C
5 : 4

B:A:C
10:15:8

217.8/33x8=52.8
52.8-5 = 47.8 kg (Carl's actual mass)

However, I think that the correct answer should be 49.16 kg (correct to 2 decimal places).

[Pen88n]

Vanilla Cake:

Vanilla Cake:

Paper 2
Q13. 20 boys
Q16. (a) 54 litres (b) 20 cm

Pen88n:

There are 2 questions whereby he has different answers compared with yours and I've checked through and his answer seems ok. Below are the 2 questions:

Q13) His ans: 34 boys
Adult: Boys : Girls => 16 : 3 : 1
Diff between boys and girls: 3u - 1u = 36 => u = 18
Adult + Girls: 17u = 18 x 17 = 306
90% are adults and girls, 10% boys: 306 / 9 = 34 boys

Q16(b) His ans: 7.5cm
After 20 mins, 6l of water drained
2 container base is 500+300 cm sq, so height will be: 6l / 800 cm sq = 7.5cm

Here's are the workings done by younger sister for the above 2 questions:

Q13
Before
Adults -> 80% ie 0.8u
Boys -> 75/100x20% = 15% ie 0.15u
Girls -> u-0.8u-0.15u = 0.05u

After
Adults -> 0.8u (No change)
Girls -> 0.05u (No change)

Adults+Girls -> 0.8u+0.05u = 0.85u -> 90%
Boys -> 10% = 0.85u/90x10 = 17u/180

Difference between boys and girls in the beginning -> 0.15u-0.05u = 0.1u
0.1u -> 36
u = 360

Boys (before) - Boys (after) = 0.15u - 17u/180 = u/18 (Boys that left)
u/18 = 360/18 = 20

Number of boys that left the hall = 20

Q16(a)
800-500 = 300
(40x50x30)-(300x20) = 54000 cm3 = 54 litres
Amount of water left in the tank after 20 minutes = 54 litres

Q16 (b)
800x20 = 16000
Assume height of the water level to be u,
(ux500)+(ux300) = 16000
u = 20 cm
Height of the water level in the 2 containers after 20 minutes = 20 cm

Alternative solution for Q16 (b) done by http://www.kiasuparents.com/kiasu/forum/viewtopic.php?f=69&t=280&start=4450 is over here.

Pen88n:

Hope to share learning. Once again, thanks for sharing.

You are most welcome!

VC,
I understand your Q13 and Q16(b) and realised where my DS has gotten wrong. Thanks again.

[Vanilla Cake]

Pen88n:

Vanilla Cake,

Btw, do you happen to have the answer to MW tuition Maths paper from the unknown school? Again, DS has only attempted paper 2, and I'm looking for an easy way out for marking instead of doing all the sums again Thanks in advance.

Hi Pen88n,
As my younger sister is doing the P6 Prelim Chinese papers at this moment, I will get her to do the MW tuition Maths paper from the unknown school by tomorrow. Will post her answers for paper 2 by tomorrow's afternoon.
Thks for your understanding.

[Pen88n]

Vanilla Cake:

Vanilla Cake:

Paper 2

Q10. 49.16 kg (correct to 2 decimal places)

Pen88n:

As usual, DS only attempted paper 2. There is a question with a different answer:
Q10) His ans: 47.8kg
Total of 3 boys: 72.6kg x 3 = 217.8kg
C:B:A = 8:10:15
Carl's weight without considering defect: 8/33 x 217.8kg = 52.8kg
Consider defective: 52.8kg - 5kg = 47.8kg

Note: the defective scale is affecting the 3 boys each 5kg difference. If you minus off 15kg difference from the total, based on the ratio of the boys' weight, it will be inaccurate as it is thus not the same 5kg difference for each boy.

Q10 is a controversial question and the answer depends on how you interpret it. In fact, I have posted it over http://www.kiasuparents.com/kiasu/forum/viewtopic.php?f=69&t=280&start=4320 and hope to get some replies.

My younger sister also did the way that your DS did to get 47.8 kg.

72.6x3 = 217.8
B : A
2 : 3

B : C
5 : 4

B:A:C
10:15:8

217.8/33x8=52.8
52.8-5 = 47.8 kg (Carl's actual mass)

However, I think that the correct answer should be 49.16 kg (correct to 2 decimal places).

I've attempted to work backwards with the 2 answers, and I must say your answer is correct as it actually provides the correct ratio between A:B:C. I've not quite figure out the exact reasoning yet.......something for me to dream about tonight.

You and your sis are quite strong in your Maths foundation. Thanks for your sharing!