Q&A - PSLE Math

[Vanilla Cake]

Dear Brenda10,


Sorry to bother you. Could you pls visit P6 Nanyang Maths CA1 2010 Paper 1 Q11 [2 marks]. It's on tessallation.
The answer given is option (2) which is 2 unit shapes have been tessellated wrongly. But my younger sister (P5) thinks it should be option (4) ie 4 unit shapes have been tessellated wrongly.

Pls help to solve this question and thanks for your time cum effort.

[Brenda10]

Vanilla Cake:

Brenda10:

Hi all, need your help on the following question.

Rosyth 2010 CA1 P2 Q16 (given answer Fazillah:39, Linda: 35)

Dear Brenda10,
Checked with my younger sister's papers for this school and the given answers are correct ie Fazillah: 39 and Linda: 65

Brenda10:

Fazillah, Linda and Winnie each owned a collection of comics. The total collection owned by Linda and Winnie was 3/2 as many comics as Fazillah owned. Linda owned 4/5 as many comics as the total collection owned by Fazillah and Winnie. If Winnie owned 169 fewer comis than Linda, how many comics must Fazillah and Linda each give to Winnie in order for the three girls to have the same number of comics ?

My younger sister's workings
L+W : F
3 : 2
27 : 18

L : F+W
4 : 5
20 : 25

F: 18u
L: 20u
W: 7u

13u=169

(18u+20u+7u)/3=15u
18u-15u=3u
3u=39 (F)
20u-15u=5u
5u=65 (L)

Fazillah and Linda must gave up 39 comics and 65 comics respectively to Winnie in order for the three girls to have the same number of comics.

Off topic, you had mentioned in another thread that you had bought some science assessment books for your DD to read and understand how these answers are worded. If you don't mind, pls share the title of these books.Also thks for your reply for the 2 questions on P6 English in another thread.

Hi Vanilla Cake

Thank you for your fast respond. I'm happy that dd will take PSLE same year with your sister.

Yes. There was a typing error and the answer key was 65 not 35. Thank you for your highlight.

The two science books that I bought were:

Science 5 & 6 Teacher Circle - JustEducation
Science Process Skills - Teacher@work

Thank you and looking forward to learn more from you. :lol:

[Brenda10]

Vanilla Cake:

Dear Brenda10,


Sorry to bother you. Could you pls visit P6 Nanyang Maths CA1 2010 Paper 1 Q11 [2 marks]. It's on tessallation.
The answer given is option (2) which is 2 unit shapes have been tessellated wrongly. But my younger sister (P5) thinks it should be option (4) ie 4 unit shapes have been tessellated wrongly.

Pls help to solve this question and thanks for your time cum effort.

Hi Vanilla Cake

Don't need to say sorry and I think we have more to learn from you.

Now dd is still in the bed. Will let her try this particular question and see what the answer is and get back to you soon.

Thank you

[Brenda10]

Brenda10:

Vanilla Cake:

Dear Brenda10,


Sorry to bother you. Could you pls visit P6 Nanyang Maths CA1 2010 Paper 1 Q11 [2 marks]. It's on tessallation.
The answer given is option (2) which is 2 unit shapes have been tessellated wrongly. But my younger sister (P5) thinks it should be option (4) ie 4 unit shapes have been tessellated wrongly.

Pls help to solve this question and thanks for your time cum effort.

Hi Vanilla Cake

Don't need to say sorry and I think we have more to learn from you.

Now dd is still in the bed. Will let her try this particular question and see what the answer is and get back to you soon.

Thank you

Hi Vanilla Cake

DD answer is Option 2. She said there was a one in the center shap out and the last one should not leave a gap otherwise it will create problem (soemthing like overlap) when continuous to tessellate.

Thank you

[Dharma]

atutor2001:

meimeitan:

Hi!


thanks for your prompt reply. The answer given is 176 and the word maximum is underlined and bloded to remind students that the answer should be miximum. Any idea?

thanks :lol:

Sorry lah. I think high think low, think left, think right, still can't put in the extra 20 pyramids. Hopefully one of the experts here will post the correct method soon.

If we arrange the 6 pyramids in a row with the base at the bottom and place 1 inverted pyramid between every pyramids placed earlier, you will have 11 pyramids i.e.(6 +5) along the length of 6cm.

Since the base is 6cm x 4cm; we can have 3 more of the same rows giving us 11 x 4 = 44 pyramids in 1 layer.

The height is 4cm. So we have 4 layers; giving us 44 x 4 = 176 pyramids.


http://postimage.org/image/2st6kykw4/

[atutor2001]

Dharma:

If we arrange the 6 pyramids in a row with the base at the bottom and place 1 inverted pyramid between every pyramids placed earlier, you will have 11 pyramids i.e.(6 +5) along the length of 6cm.

Since the base is 6cm x 4cm; we can have 3 more of the same rows giving us 11 x 4 = 44 pyramids in 1 layer.

The height is 4cm. So we have 4 layers; giving us 44 x 4 = 176 pyramids.


http://postimage.org/image/2st6kykw4/

Thank you Dharma

I keep thinking that the inverted layer can only put 3 instead of 4 on the 4cm side. Your picture tells the whole story.

[meimeitan]

Hi! Dharma and Autor2001


Thanks for both of your explanation.

[Vanilla Cake]

Brenda10:

Hi Vanilla Cake


DD answer is Option 2. She said there was a one in the center shap out and the last one should not leave a gap otherwise it will create problem (soemthing like overlap) when continuous to tessellate.

Thank you

Hi Brenda10,
Thks for your reply but she was still not convinced that the answer was option 2. Hope that someone will be able to scan the diagram for this question and post it in KSP forum.

Have your DD tried Rosyth 2010 P6 CA1 Maths - Paper 2 Q11? The answer for the average height of the 3 girls is 304 cm. 304 cm is not a realistic figure in the real world.

Here's the question:
The ratio of Amy's height to Betty's height is 1:2. The ratio of Betty's height to Carmen's height is 3:5. Betty is 144 cm taller than Amy. What is the average height of the 3 girls?

[Brenda10]

Vanilla Cake:

Brenda10:

Hi Vanilla Cake


DD answer is Option 2. She said there was a one in the center shap out and the last one should not leave a gap otherwise it will create problem (soemthing like overlap) when continuous to tessellate.

Thank you

Hi Brenda10,
Thks for your reply but she was still not convinced that the answer was option 2. Hope that someone will be able to scan the diagram for this question and post it in KSP forum.

Have your DD tried Rosyth 2010 P6 CA1 Maths - Paper 2 Q11? The answer for the average height of the 3 girls is 304 cm. 304 cm is not a realistic figure in the real world.

Here's the question:
The ratio of Amy's height to Betty's height is 1:2. The ratio of Betty's height to Carmen's height is 3:5. Betty is 144 cm taller than Amy. What is the average height of the 3 girls?

Dear VC,

OIS. You're right that 304cm is not realistic. However, I did not check in details so long as DD answer is matching with the answer key. Thank you for your highlight.

Off topic, there is one MCQ in Kong Kwa 2010 CL CA1 Q6 answer should be option 2 instead of option 4. I think the answer key provided wrongly. You may want to have a look.

Thank you.

[Vanilla Cake]

Brenda10:

Off topic, there is one MCQ in Kong Kwa 2010 CL CA1 Q6 answer should be option 2 instead of option 4. I think the answer key provided wrongly. You may want to have a look.Thank you.

Here's the question from P6 Kong Hwa Maths CA1 2010 Paper Q6:

Joshua swam 2000 m yesterday. Luke swam 400 m less than Joshua. Find the ratio of the distance swam by Joshua to the total distance swam by Joshua and Luke.

Options:
(1) 2000:400
(2) 2000:1600
(3) 2000:2400
(4) 2000:3600

Answer given was option 4 which was correct.

Workings
Distance that Joshua swam = 2000 m
Distance that Luke swam = 2000 m - 400 m = 1600 m
Total distance swam by Joshua and Luke = 2000 m + 1600 m = 3600 m
Ratio of the distance swam by Joshua to the total distance swam by Joshua and Luke = 2000:3600
ie option (4).

Thks.