Tutor MathsGuru: Ask me for your burning Maths questions!

[Dharma]

benorito:

This is from Red Swastika Prelim 2010 Q 8:


Raju and Gywneth shared some sweets. If Raju gave 1/2 of his share to Gywneth, Gywneth will have 8 more sweets from Raju. If Raju gave 1/4 of his share to Gywneth, Gywneth would have 2 more sweets than Raju. How many sweets did Raju have at first ?

The given answer was 12. Is this correct ?

1/2 - (-1/2) = 1 whole => 8
1/4 - (-1/4) = 1/2 => 2

Diff = 1/2 => 8 - 2 = 6
1 whole => 12 ( total number of sweets Raju had at first )

[YLH88]

Hi,


Need help with the below 2 questions :

1) Nanyang 2010 P6 Prelim paper 1 Qn 21
The cost of 3 mangoes is the same as the cost of 5 grapefruits.
The cost of 3 mangoes is also the same as the cost of 10 pears.
Find the ratio of the cost of a mango to the cost of a grapefruit to the cost of a pear.
(ans : 10 : 6 : 3)

2) Nanyang 2010 P6 Prelim paper 1 Qn 30
The figure below is formed by stacking 4 pieces of square paper one on top of another. The papers have different prints and sizes (of sides 3cm, 4cm, 5cm and 6cm).
The 6-cm piece is placed at the bottom of the stack, followed by the 5-cm piece, then the 4-cm piece and the 3-cm piece is placed right on top.
Find the sum of the area A and B.
(ans : 8 cm2)

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


Thank you very much!

[Dharma]

[Moderator's note: Article edited & selected for http://www.kiasuparents.com/kiasu/content/some-questions-and-answers-primary-6-math]

YLH88:

Hi,

Need help with the below 2 questions :

1) Nanyang 2010 P6 Prelim paper 1 Qn 21
The cost of 3 mangoes is the same as the cost of 5 grapefruits.
The cost of 3 mangoes is also the same as the cost of 10 pears.
Find the ratio of the cost of a mango to the cost of a grapefruit to the cost of a pear.
(ans : 10 : 6 : 3)

2) Nanyang 2010 P6 Prelim paper 1 Qn 30
The figure below is formed by stacking 4 pieces of square paper one on top of another. The papers have different prints and sizes (of sides 3cm, 4cm, 5cm and 6cm).
The 6-cm piece is placed at the bottom of the stack, followed by the 5-cm piece, then the 4-cm piece and the 3-cm piece is placed right on top.
Find the sum of the area A and B.
(ans : 8 cm2)

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


Thank you very much!

Nanyang 2010 P6 Prelim paper 1 Qn 21
3M = 5G
1M = 5/3 G
1M : 1G = 5 : 3 = 10 : 6

3M = 10P
1M = 10/3 P
1M : 1P = 10 : 3

1M : 1G : 1P = 10 : 6 : 3

Nanyang 2010 P6 Prelim paper 1 Qn 30
Area of large square – Area of yellow square = 6^2 – 3^2 = 36 – 9 = 27
Yellow square => 3 x 3
Orange square => 4 x 4
White square => 5 x 5
Blue square => 6 x 6

Length of A = Width of A = 6 - 4 = 2
Area of A = 2 X 2 = 4
Area of A = Area of B [Symmetry]
Area of A + Area of B = 4cm2 x 2 = 8cm2

[little_twin_stars]

Dear all,


May I know is there any good books to learn and practice Mathematics Solving? I think I really need it in order to understand and prepare myself when I teach my daughter.

TIA.

[ganchiong]

Need help in the following question:


Jeffrey wants to pack some identical cuboids into a container. What is the maximum number of cuboids Jeffrey can pack into the container?

Dimension for cuboid:2cmx2cmx3cm and container: 6cmx11cmx14cm

TIA

[corneyAmber]

ganchiong:

Need help in the following question:


Jeffrey wants to pack some identical cuboids into a container. What is the maximum number of cuboids Jeffrey can pack into the container?

Dimension for cuboid:2cmx2cmx3cm and container: 6cmx11cmx14cm

TIA

is the answer 77?

[ganchiong]

ksi:

ganchiong:

Need help in the following question:


Jeffrey wants to pack some identical cuboids into a container. What is the maximum number of cuboids Jeffrey can pack into the container?

Dimension for cuboid:2cmx2cmx3cm and container: 6cmx11cmx14cm

TIA

is the answer 77?

yes

[corneyAmber]

ganchiong:

ksi:

[quote=\"ganchiong\"]Need help in the following question:


Jeffrey wants to pack some identical cuboids into a container. What is the maximum number of cuboids Jeffrey can pack into the container?

Dimension for cuboid:2cmx2cmx3cm and container: 6cmx11cmx14cm

TIA

is the answer 77?

yes[/quote]container = 6x11x14 = 924
cuboid = 2x2x3 = 12
max. Number of cuboids = 924/12 = 77

[kancheongmum]

ksi:

ganchiong:

[quote=\"ksi\"]
is the answer 77?

yes

container = 6x11x14 = 924
cuboid = 2x2x3 = 12
max. Number of cuboids = 924/12 = 77[/quote]Hi ksi and ganchiong
I don't think the answer is 77. You cannot divide the volume of the container by the volume of the cuboid. You have to approach this type of question this way. Minimize the remainder. Divide each dimension by each dimension. Try not to have remainder.

6/3 -- 2 cuboids
11/2 -- 5 cuboids remain 1 cm
14/2 -- 7 cuboids

Max no. 2 x 5 x 7 = 70 cuboids

[snowman.022851697]

Yes kancheongmum is right. You can’t squeeze a 2-cm cube into a 1-cm space. Reason being simple: solids can’t be compressed…


If you use a calculator and end up with decimal, round down, not up, to the nearest whole number