Tutor MathsGuru: Ask me for your burning Maths questions!

[Guan Hui]

The number of marbles in Box A, Box B and Box C was 195.

John added 60 marbles to those in Box A, doubled the number of marbles in Box B and halved the number of marbles in Box C.
The ratio of the number of marbles becomes 4:1:2.
What is the total number of marbles in the three boxes now?

final ratio
4u:1u:2u
initial
4u-60: 0.5u : 4u

4u-60 +0.5u +4u=8.5u-60
8.5u=195+60
8.5u=255
1u=30marbles

final ratio
4u+1u+2u=7u
7x30=210 marbles=D

[SoWoW]

Hi,


Please help to clarify!

Mrs Wong wants to pack 100 buns in boxes for her son to take to his class party. Each box can hold up to a max. of 8 buns. What is the minimum no. of boxes she will need to pack all the buns?

Should the answer be 12 or 13?
If the answer is 12, can help to explain why 12?

Thanks alot

[Dharma]

SoWoW:

Hi,


Please help to clarify!

Mrs Wong wants to pack 100 buns in boxes for her son to take to his class party. Each box can hold up to a max. of 8 buns. What is the minimum no. of boxes she will need to pack all the buns?

Should the answer be 12 or 13?
If the answer is 12, can help to explain why 12?

Thanks alot

Mrs Wong will need 13 boxes. She will pack 12 boxes with 8 buns each. The remaining 4 buns will be packed into another box. (12 + 1 = 13)

The answer cannot be 12 boxes, otherwise the remaining 4 buns will be left unpacked.

[SoWoW]

Dharma:

Mrs Wong will need 13 boxes. She will pack 12 boxes with 8 buns each. The remaining 4 buns will be packed into another box. (12 + 1 = 13)


The answer cannot be 12 boxes, otherwise the remaining 4 buns will be left unpacked.

Hi Dharma,

thank you so much. The answer provided is 12 so it's a wrong answer.
thanks for your clarifications. cheers

[Vanilla Cake]

Hi Mathsguru,

Could you pls help to post your approach to solve this 5-mark question from http://www.orlesson.org/orp/09Ma/2009-Math-SA1-AiTong.pdf?
There are workings for the solution but both of us (my P5 younger sister and myself)cannot understand them :oops:.Pls refer to page 27 of the PDF for the workings.

Devi had 26 more $5 notes than $10 notes. After paying $480 for a camera with some of the $5 notes, she had 6 times as many $10 notes as $5 notes.
a) How many $5 notes did Devi have at first?
b) How much money did Devi have left?

Could the model solution be applicable for such problem sum?
Thanks for your help.

[adhdadhd]

Vanilla Cake:

Hi Mathsguru,

Pls help my P5 younger sister to solve this 4-mark question from http://www.orlesson.org/orp/09Ma/2009-Math-SA1-ACS.pdf using models. Thank you.

The volume of water in bottle P was 3/5 of that in bottle Q. After 60 ml of water was added to bottle P and 20 ml was poured away from bottle Q, the amount of water in bottle P was 3/4 that in bottle Q. What was the amount in each bottle at first?

Other than models, what are your recommended method/s to tackle such problem sum?

This is how I would use model to solve this problem:

http://www.postimage.org/image.php?v=Pqs4xsA
[/img]

[adhdadhd]

Vanilla Cake:

Hi Mathsguru,

Could you pls help to post your approach to solve this ....

Devi had 26 more $5 notes than $10 notes. After paying $480 for a camera with some of the $5 notes, she had 6 times as many $10 notes as $5 notes.
a) How many $5 notes did Devi have at first?
b) How much money did Devi have left?

Could the model solution be applicable for such problem sum?
Thanks for your help.

Hi, let me take the liberty before mathguru response ..

First, $480 worked out to be 96 pcs of $5 notes.



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

Thus, 5 units = 70 notes, 1 unit = 14 notes.

a) Devi has at first, 14 + 96 = 110 notes.

b) Devi has left with 14 x $5 + 84 x $10 = $910.

Hope it helps, apologize for the small image..

[mathsguru]

lemofish:

I have a question:


40 children in Class A are having a muffin party. 26 of them eat a vanilla muffin each and 32 of them eat a chocolate muffin each. Everyone in the class eats at least 1 muffin. How many children eat both a vanilla muffin and a chocolate muffin?

Hi Lemofish,

Here's my solution. Hope it helps!


MathsGuru

http://www.postimage.org/image.php?v=gxJkNg0

[mathsguru]

Vanilla Cake:

Hi Mathsguru,

Pls help my P5 younger sister to solve this 4-mark question from http://www.orlesson.org/orp/09Ma/2009-Math-SA1-ACS.pdf using models. Thank you.

The volume of water in bottle P was 3/5 of that in bottle Q. After 60 ml of water was added to bottle P and 20 ml was poured away from bottle Q, the amount of water in bottle P was 3/4 that in bottle Q. What was the amount in each bottle at first?

Other than models, what are your recommended method/s to tackle such problem sum?

Hi Vanilla Cake,

Here's my solution. Hope it can help your sis!

For primary school level, I would still advocate the use of models to do this problem. Easier to understand and it's also faster and more accurate.

The trick is to get ourselves familiar with expressing the new amount in terms of the old one. Like in this question, P has 3 units at first. So after adding 60ml, P still has 3 units. This implies that each unit is bigger by 20ml now.

Using this, we can draw Q's amount according to the ratios given. Very quickly, we can identify what's 1 unit.

Cheers,
MathsGuru

http://www.postimage.org/image.php?v=aVe5uj9

[mathsguru]

OK Lor:

Hi Mathsguru,


The product of two numbers, A and B, is 108. The difference betweeen A and B is a common factor of A and B. Find the values of A and B.

Thanks.

Hi OK Lor,

Here's my solution.


MathsGuru

http://www.postimage.org/image.php?v=gxJlCE0