Tutor MathsGuru: Ask me for your burning Maths questions!

[pineapple tarts]

Dear Mathsguru,


wow.... many thanks for your solutions. It's very clear but I still need some time to digest it :oops: I wonder how these P5/6 handle such questions. Anyway, I just want to say thank you!

And thanks to Dharma too

[Vanilla Cake]

firebird:

Please help me on the following P6 math:


1) Ali and Bala had a total of 1134 marbels. After each of them had given away some marbles, the number of marbles Ali has was 4 times the number of marbles he had given away and the number of marbles Bala had was 3 times the number of marbles he had given away. They had a total of 897 marbles left. How many marbles did Bala had first?

My working via simultaneous equation a) 5 Ali + 4 Bala = 1,134
b) 4 Ali + 3 Bala = 897 and c) Subtracting b from a is 1 Ali + 1 Bala =237
MY ANSWER IS 204 FOR BALA (which was the given answer).

Is this question (4 marks) from Pei Chun P6 CA1 2009 paper 2 Q11? http://www.orlesson.org/orp/09Ma/2009-P6-Math-CA1-PeiChun.pdf.

[trytry]

firebird:

Dear Mathsguru


Good morning.

Please help me on the following P6 math:

1) Ali and Bala had a total of 1134 marbels. After each of them had given away some marbles, the number of marbles Ali has was 4 times the number of marbles he had given away and the number of marbles Bala had was 3 times the number of marbles he had given away. They had a total of 897 marbles left. How many marbles did Bala had first?

My working via simultaneous equation a) 5 Ali + 4 Bala = 1,134
b) 4 Ali + 3 Bala = 897 and c) Subtracting b from a is 1 Ali + 1 Bala =237
MY ANSWER IS 204 FOR BALA (which was the given answer).

Please let me know:
(i) Is simultaneous equation method to find solution allowed for PSLE?
(ii) How to find the solution based on model mehtod for the question 1.


Thank you.
firebird

Before
ALI.................A...A....A....A....A....|
Bala................B...B....B....B.........|.....1134
......................{...4groups..}....A=1134-948=186
.........................=.948...............

After
ALI.......................A....A....A....A........|
Bala......................B....B....B..............|....897


1 group of A and B = 1134-897=237

4 group of A and B=237 x4=948

therefore 1A=1134-948=186

ALi has 5A=186*5=930
then BALA has 1134-930=204 at first



Hope you understand

[Dharma]

firebird:

Dear Mathsguru


Good evening.

Please help me on the following P6 maths:

1) If Ahmad and Ben work together, they can compete a job in 12 days. If Ahmad and Ben worked together for 3 days, followed by Ben who worked alone for the next 5 days, they can finish 5/12(fraction) of the job. How many days will each of them need to complete the job if they work alone?

2) Allyson, Betty and Charlene shared to buy a watch for their father. Allyson paid 1/4(fraction) of the total share of Betty and Charlene. Betty paid 1/5 (fracion) the total share of Allyson and Charlene. If Charlene paid $56 more than Betty, how much did the watch cost?

Many thanks
firebird

1) If Ahmad and Ben work together, they can compete a job in 12 days. If Ahmad and Ben worked together for 3 days, followed by Ben who worked alone for the next 5 days, they can finish 5/12(fraction) of the job. How many days will each of them need to complete the job if they work alone?

A & B – 12 days – 1 job
A & B – 1 day – 1/12 job
A & B – 3 days – ¼ job

B alone – 5 days – (5/12 – ¼) job = 1/6 job
B alone – 1/6job – 5 days
B alone – 6/6 job – 5 x 6 = 30 days
B alone – 1 day – 1/30 job

A alone – 1 day – (1/12 – 1/30)job = (5/60 – 2/60)job = 3/60 job = 1/20 job
A alone – 20/20 job – 20 days

If they work alone; A will take 20 days and B will take 30 days to complete the job.

2) Allyson, Betty and Charlene shared to buy a watch for their father. Allyson paid 1/4(fraction) of the total share of Betty and Charlene. Betty paid 1/5 (fracion) the total share of Allyson and Charlene. If Charlene paid $56 more than Betty, how much did the watch cost?

A : 1u
B & C : 4u

B : 1p
A & C : 5p

A : B : C = 1u : 1p : 4u – 1p or = 1u : 1p : 5p – 1u

4u – 1p = 5p – 1u
5u = 6p

A : B : C = 1u : 5/6u : 25/6u – 1u = 1u : 5/6u : 19/6u = 6u : 5u : 19u
19u – 5u = $56
14u = $56
1u = $4

Cost of watch = 30u = 30 x $4 = $120

[YLH88]

Hi Mathsguru,


Need your help with the 2 questions below :

1) Mrs Yee had 60% more books than Mdm Ling. Miss Tang had 25% fewer books than Mrs Yee. Mrs Yee and Mdm Ling gave Miss Tang some books in the ratio of 3 : 1. As a result, Miss Tang had 1 1/2 times as many books as before. Given that Mrs Yee had 240 more books than Mdm Ling in the end, how many books did Mrs Yee give to Miss Tang ?

I tried solving the question and got the answer = 90, is it correct ?

2) In the figure below not drawn to scale, the area of the triangle is 250% of the area of the rectangle. The unshaded part of the triangle is 300% of the unshaded part of the rectangle. Find the area of the shaded part if the area of the rectangle is 64 cm2.

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

Thank you so much!

[mathsguru]

firebird:

Dear Mathsguru


Good evening.

Please help me on the following P6 maths:

1) If Ahmad and Ben work together, they can compete a job in 12 days. If Ahmad and Ben worked together for 3 days, followed by Ben who worked alone for the next 5 days, they can finish 5/12(fraction) of the job. How many days will each of them need to complete the job if they work alone?

2) Allyson, Betty and Charlene shared to buy a watch for their father. Allyson paid 1/4(fraction) of the total share of Betty and Charlene. Betty paid 1/5 (fracion) the total share of Allyson and Charlene. If Charlene paid $56 more than Betty, how much did the watch cost?

Many thanks
firebird

Hi Firebird,

Here are my solutions. Hope they help!


MathsGuru

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

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

[mathsguru]

firebird:

Dear Mathsguru


Good morning.

Please help me on the following P6 math:

1) Ali and Bala had a total of 1134 marbels. After each of them had given away some marbles, the number of marbles Ali has was 4 times the number of marbles he had given away and the number of marbles Bala had was 3 times the number of marbles he had given away. They had a total of 897 marbles left. How many marbles did Bala had first?

My working via simultaneous equation a) 5 Ali + 4 Bala = 1,134
b) 4 Ali + 3 Bala = 897 and c) Subtracting b from a is 1 Ali + 1 Bala =237
MY ANSWER IS 204 FOR BALA (which was the given answer).

Please let me know:
(i) Is simultaneous equation method to find solution allowed for PSLE?
(ii) How to find the solution based on model mehtod for the question 1.


Thank you.
firebird

Hi Firebird,

In my opinion, I think it's the extent in which the simultaneous equations are being applied. It may be confusing for a P6 student to understand simultaneous equations in pure algrabraic sense as they have only learnt basic algebra in P6. However, for this question, what you've done is actually a very simple form of applying simultaneous equations, which is definitely acceptable! Diagrams/models are not necessary, but are good for visualisation, in case the student cannot \"see\" what minus what or what plus what.

Here's my solution anyway.

Cheers,
MathsGuru

http://www.postimage.org/image.php?v=PqIi199

[mathsguru]

YLH88:

Hi Mathsguru,


Need your help with the 2 questions below :

1) Mrs Yee had 60% more books than Mdm Ling. Miss Tang had 25% fewer books than Mrs Yee. Mrs Yee and Mdm Ling gave Miss Tang some books in the ratio of 3 : 1. As a result, Miss Tang had 1 1/2 times as many books as before. Given that Mrs Yee had 240 more books than Mdm Ling in the end, how many books did Mrs Yee give to Miss Tang ?

I tried solving the question and got the answer = 90, is it correct ?

2) In the figure below not drawn to scale, the area of the triangle is 250% of the area of the rectangle. The unshaded part of the triangle is 300% of the unshaded part of the rectangle. Find the area of the shaded part if the area of the rectangle is 64 cm2.

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

Thank you so much!

Hi YLH88,

Here are my solutions. I didn't get 90 books for the 1st question. Perhaps you take a look at my solution and see if my understanding of the question is right? I double-checked my answer...think it should be correct.

Cheers,
MathsGuru

http://www.postimage.org/image.php?v=TsjhX9

http://www.postimage.org/image.php?v=aVtw09r

[firebird]

Dear Mathsguru


Good morning.

Please help me on the P6 maths:

1) What is the value of 18- 6 + 2 x 5?

My working is 2 x 5 equal 10
6 + 10 equal 16
18 - 16 equal 4

However, the given answer was 22.
My understanding was to follow this sequence:
division, multipilication, addtion and substraction. Please correct me.

2) Given 21 boxes. The 1st has 3 marbles, 2nd box has 6 marbles, 3rd box has 9 marbles and so on in this pattern. What is the total number marbles in all the 21 boxes?

By adding one by one I can get answer 693

My request is: any short cut as this is a 1 mark question?

Many thanks
firebird

[YLH88]

Hi Mathsguru,


I’m definitely sure your answer is correct But need you to help explain some queries :

For Qn 1 on the books, why do we need to break the 1 big unit into 4 units ? I thought 3 : 1 is referring to the original units where Mrs Yee has 6 units (160%) and Mdm Ling has 5 units (100%) ?

For Qn 2 on the diagram, 160 - shaded area = 3 x (64 - shaded area), multiple by 3 is it because of the unshaded triangle is 300% of the unshaded rectangle ?

Thank you very much !