Tutor MathsGuru: Ask me for your burning Maths questions!

[tianzhu]

Hi


Hope this helps.
The drawing is not drawn to scale.

Best wishes
http://farm5.static.flickr.com/4116/4944993552_7c6bcaebd8_z.jpg\">

[tiger262]

tianzhu:

Hi


Hope this helps.
The drawing is not drawn to scale.

Best wishes

Hi Tianzhu,

Thank you very much for the brilliant drawing with superb clarity. You are truly a wizard when it comes to drawings, models and pictures.

Thanks and Regards.

[Almighty]

Almighty:

Almighty:

Hi all,

The question :
A rectangular block of wood, 47 cm long, 38 cm wide, and 24 cm high , was cut into equal cubes of edge 4 cm.
a) What was the maximum number of 4cm cubes which I could cut?
b) What was the total surface area of the remaining piece of wood?

a) my answer : 594 cubes
b) Book answer : 256cm2. My answer is different.Can anyone halp on
section(B)
Thankyou in advance..

Hi Dharma Sir,
This question of mine is unanswered/Can u help me with sec (B)?
Thankyou

Thankyou everyone who spent time to clarify my doubt.Will go through them.

[maths6a]

acehkr3009:

Hi all,


Here is a Before & After question that I come across on one assessment....

Yesterday, Peter has 689 Singapore and Malaysia stamps. This morning, he used 2/5 of his Singapore stamps to exchange for 31 Malaysia stamps. As a result, he now has equal number of Singapore and Malaysia stamps. How many Malaysia does he has yesterday?

Can someone used Model and algebra to solve this question.

Appreciate with Thanks.

Since no one has helped with this one, let me try.

Since 2/5 of S'pore stamps used, there will be 3/5 of S'pore stamps left.
Since Sing = Malaysian after 31 Malaysian added, we start with 3 units for Sing and Malaysian.
S ---- 3 units + 2 units = 5 units at first
M ---- 3 units - 31 at first
5 units + 3 unit - 31 = 689
8 units = 689 + 31
8 units = 720
1 unit = 90
3 units - 31 = 3 x 90 - 31 = 239
Let me know if you still need the model method.

[speedmaths.012624com]

favianboy:

2 candles A & B, A is fatter and takes 5 hours to burn. B is thinner and takes 4 hours to burn. They are the same height. At which point A is twice the height of B.


Pls help

Did anyone get the answer as 10/3 or 3 1/3 hours?

[super star]

hi

I went through the problem & the working .but still cannot understand that.please explain this problem

maths6a:

beauty queen:

Please help me with this question,

There are some black and white marbles in a bag. If 20 black marbles are removed from the bag, the total number of marbles left will be 7 times the number of black marbles left. If 50 white marbles are removed from the bag, the total number of marbles left will be 5 times the number of black marbles left. How many marbles are there in the bag.

http://www.postimage.org/image.php?v=aVmQl6J
[/img]

[maths6a]

super star:

hi

I went through the problem & the working .but still cannot understand that.please explain this problem

maths6a:

[quote=\"beauty queen\"]Please help me with this question,

There are some black and white marbles in a bag. If 20 black marbles are removed from the bag, the total number of marbles left will be 7 times the number of black marbles left. If 50 white marbles are removed from the bag, the total number of marbles left will be 5 times the number of black marbles left. How many marbles are there in the bag.

Using algebra which in this case is cross multiplication:
When you remove 20 black marbles, the ratio of total marbles left to black marbles left is 7 : 1 so
white to black will be 6 : 1.
so number of white to black at first will be
6 units : 1 unit + 20
then question says to remove 50 white marbles are from the bag so
whilte --- 6 units - 50 ------- 4 equation 1
black ---- 1 unit + 20 -------1 equation 2
multplying equation 2 by 4 because the LCM of 1 and 4 is 4,
equation 2 becomes 4 units + 80
so now 6 units - 50 ---- 4 units + 80
2 units = 80 + 50 = 130
1 unit = 65
number of marbles in the bag = 7 units + 20
= 475
Hope this method is easier for you?






http://www.postimage.org/image.php?v=aVmQl6J
[/img]

[/quote]

[Cheerfuldad]

Hi all,


Please help!

Q1. Kailing and Jim had a total of $63. Kailing gave 0.3 of her share to Jim. Jim then gave 1/3 of the total amount of money he had to his brother. In the end, all the three children had the same amount of money. How much money did Kailing have at first?

Q2. A stack of bookmarks was shared among Peter, Tom and Jerry. Peter received 3 more than 50% of the bookmarks. Tom received 5 more than half of the remaining bookmarks. After Peter and Tom had taken their share. Jerry received 50% of the remainder and the last 3 bookmarks. What percentage of the stack of bookmarks did Jerry receive?

Q3. A dressmaker had some buttons. She used 1/7 of them on Monday and 1/11 of the remainder on Tuesday. On Wednesday, she bought 255 buttons and then had as many buttons as she had at first. How many buttons did she have at first?

Q4. A group of boys played only two types of sport during recess. 1/4 of them played badminton and 2/3 of them played football. 1/6 of the boys played both sports and 90 boys did not play any sports at all. How many boys were there?

TIA!

[Vanilla Cake]

Cheerfuldad:

Q1. Kailing and Jim had a total of $63. Kailing gave 0.3 of her share to Jim. Jim then gave 1/3 of the total amount of money he had to his brother. In the end, all the three children had the same amount of money. How much money did Kailing have at first?

Refer to http://www.onsponge.com/forum/35-thinkingmathonsponge/4321-p5-working-backwards.html.
This is a 5-mark question from Nanyang Primary School 2009 P5 CA2 paper 2 Q18.

Cheerfuldad:

Q2. A stack of bookmarks was shared among Peter, Tom and Jerry. Peter received 3 more than 50% of the bookmarks. Tom received 5 more than half of the remaining bookmarks. After Peter and Tom had taken their share. Jerry received 50% of the remainder and the last 3 bookmarks. What percentage of the stack of bookmarks did Jerry receive?

Refer to http://www.onsponge.com/forum/35-thinkingmathonsponge/4310-pr-5-remainder-concept.html#4325.
This is a 5-mark question from Nanyang Primary School 2009 P5 CA2 paper 2 Q17.

Cheerfuldad:

Q3. A dressmaker had some buttons. She used 1/7 of them on Monday and 1/11 of the remainder on Tuesday. On Wednesday, she bought 255 buttons and then had as many buttons as she had at first. How many buttons did she have at first?

6/7x10/11=60/77
17/77-> 255
77/77 -> 1155
Number of buttons that the dressmaker had at first = 1155.

This is a 4-mark question from Nanyang Primary School 2009 P5 CA2 paper 2 Q13.

Cheerfuldad:

Q4. A group of boys played only two types of sport during recess. 1/4 of them played badminton and 2/3 of them played football. 1/6 of the boys played both sports and 90 boys did not play any sports at all. How many boys were there?

1/4-1/6=1/12
2/3-1/6=1/2
1-1/12-1/2-1/6=1/4

1/4->90
4/4-> 90x4=360
Number of boys = 360

This is a 3-mark question from Nanyang Primary School 2009 P5 CA2 paper 2 Q6.

For the benefits of readers in this forum, it's good if you are able to state the source of your questions and given answers if available.This will help to save time for potential problem solvers rendering their help to your questions.
Thanks.

VC's mum

[tiger262]

tianzhu:

Hi


Hope this helps.
The drawing is not drawn to scale.

Best wishes
http://farm5.static.flickr.com/4116/4944993552_7c6bcaebd8_z.jpg\">

Hi Dharma,

This is regarding the question about 4-cm cubes being cut out of a wooden block, leaving behind a 'L-shaped' wooden block.

Tianzhu has kindly provided a neat diagram with dimensions for the L-shaped block. Can you please provide the solution for calculating the total surface area of the left-over L-shaped block? Please help.

Thanks a lot.