Tutor MathsGuru: Ask me for your burning Maths questions!

[Dharma]

Bommu99:

Hi Mathsguru,


Would greatly appreciate your help to solve these 2 questions which are among the SMOPS sample questions.

Thanks,

Bommu99
http://www.postimage.org/image.php?v=gx11D_jS

Q1
(1 + 2/1) x (1 + 2/2) x (1 + 2/3) x (1 + 2/4) x (1 + 2/5) x … x (1 + 2/26) x (1 + 2/27)
= 3/1 x 4/2 x 5/3 x 6/4 x 7/5 x … x 28/26 x 29 /27
= ½ x 28 x 29
= 406

Q3

Diagram A
Area of Shaded square = 50cm2
Area isosceles triangle = 2 x 50cm2 = 100cm2
Length of 2 equal side of triangle = a
½ x a x a = 100
a^2 = 200
Base of triangle = sqrt (200 + 200) = 20
Height of triangle = 3h
½ x 20 x 3h = 100
3h = 10cm

Diagram B
Side of shaded square = 2/3 x 3h = 20/3cm
Area of shaded square = 400/9 = 44 4/9cm2

[Ngserene617]

Dharma:

Bommu99:

Hi Mathsguru,


Would greatly appreciate your help to solve these 2 questions which are among the SMOPS sample questions.

Thanks,

Bommu99
http://www.postimage.org/image.php?v=gx11D_jS

Q1
(1 + 2/1) x (1 + 2/2) x (1 + 2/3) x (1 + 2/4) x (1 + 2/5) x … x (1 + 2/26) x (1 + 2/27)
= 3/1 x 4/2 x 5/3 x 6/4 x 7/5 x … x 28/26 x 29 /27

= ½ x 28 x 29
= 40.


Q3

Diagram A


Area of Shaded square = 50cm2
Area isosceles triangle = 2 x 50cm2 = 100cm2
Length of 2 equal side of triangle = a
½ x a x a = 100
a^2 = 200
Base of triangle = sqrt (200 + 200) = 20
Height of triangle = 3h
½ x 20 x 3h = 100

3h = 10cm

Diagram B
Side of shaded square = 2/3 x 3h = 20/3cm
Area of shaded square = 400/9 = 44 4/9cm2[/quo

Hi MathsGuru,

I need help for this question:
1. Mr Gunalan has 640 books. 3/4 of them are storybooks and the remaining books are magazines and journals. 3/5 of the remaining books are magazines.
a) how many magazines does he have?
b) He wants to buy more magazines so that the number of the magazines he has will increase to 20% of the total number of books. How many more magazines must he buy?

[Ngserene617]

mathsguru:

Original Title: Let MathsGuru Answer Your Burning Maths Questions!


:welcome:

Dear Parents,

Are you frustrated/stuck when helping your child solve his/her Maths questions? Are you inclined to use Algebra most of the time? Do you have difficulty trying to use diagrams or other heuristic methods (that Primary School students learn) to solve?

:idea: Post your questions here and see how MathsGuru solve them to the best of her ability. Detailed solutions will be posted back in this thread.

So start asking and watch this space!!

Cheers :celebrate: ,
MathsGuru

P/S (Disclaimer, in case you're wondering...):
Although MathsGuru is a full-time Maths tutor, this thread is meant to be an absolutely free resource for parents (or even children) with no strings attached. Just someone who's passionate about Maths and wanna spread the fun in learning Maths with others.

Hi MathsGuru,

I need help for this Question:
1. Mr Gunalan has 640 books. 3/4 of them are storybooks and the remaining books are magazines and journals. 3/5 of the remaining books are magazines.
a) How many magazines does he have?
b) He wants to buy more magazines so that the number of magazines he has will increase to 20% of the total number of books. How many more magazines must he buy?

Thanks;)

[clblinym]

I need help for this Question:

1. Mr Gunalan has 640 books. 3/4 of them are storybooks and the remaining books are magazines and journals. 3/5 of the remaining books are magazines.
a) How many magazines does he have?
b) He wants to buy more magazines so that the number of magazines he has will increase to 20% of the total number of books. How many more magazines must he buy?

------
Below is my son’s answer.
640x ¾ = 480 (story books)
640-480=160(magazine+journal)
160 x 3/5 = 96(magazines)

b) 480+64=544 (story books and journals)
Since magazines will take up 20%, story books and journals will take up 80%.
544 –> 80%
20% –> 136
136 is the number of magazines after purchase.
136-96=40(magazines to be bought)

[super star]

pls help me with this problem

1) Container A contains 250 red marbles and 200 blue marbles. Container B contains 600 red marbles and 150 blue marbles.How many red and blue marbles must be moved from Container A to Container B such that 25% of the marbles in Container A are red and 75% of the marbles in container B are red.

[super star]

http://www.postimage.org/image.php?v=TsA0t7J

The figure is madeup of two identical rightangled triangles,a small square & a big square.the perimeter of the shaded region is 50cm,& the total area of the two square is 254.5sqcm.
find the total area of the two shaded right-angled triangle.

Pls help me with the problem.

[Vanilla Cake]

super star:

1) Container A contains 250 red marbles and 200 blue marbles. Container B contains 600 red marbles and 150 blue marbles.How many red and blue marbles must be moved from Container A to Container B such that 25% of the marbles in Container A are red and 75% of the marbles in container B are red.

This question is from RGPS 2009 P6 SA1 Paper 2 Q18 and pls refer to http://psle2010a.blogspot.com/2010/04/percentage-p6-2009-sa1-p2-rgs-q18_5512.html.

VC's mum

[Vanilla Cake]

super star:

http://www.postimage.org/image.php?v=TsA0t7J

The figure is madeup of two identical rightangled triangles,a small square & a big square.the perimeter of the shaded region is 50cm,& the total area of the two square is 254.5sqcm.
find the total area of the two shaded right-angled triangle.

This question is from RGPS 2009 P6 SA1 Paper 2 Q14 and pls refer to http://psle2010a.blogspot.com/2010/04/area-p6-2009-sa1-p2-rgs-q14_4890.html.

VC's mum

[Dharma]

super star:

pls help me with this problem

1) Container A contains 250 red marbles and 200 blue marbles. Container B contains 600 red marbles and 150 blue marbles.How many red and blue marbles must be moved from Container A to Container B such that 25% of the marbles in Container A are red and 75% of the marbles in container B are red.

Red : 250 + 600 = 850
Blue : 200 + 150 = 350

25%A + 75%B = 850 ------------- (1)
75%A + 25%B = 350 -------------(2)

100%A + 100%B = 1200 ------------(1) + (2)
100%A + 300%B = 3400 -------------(1) X 4
200%B = 3400 – 1200 = 2200
100%B = 1100
100%A = 100

No. of red and blue marbles transferred from Container A to B
= (250 + 200) – 100 = 350

[super star]

THANK YOU :lol:

Dharma:

super star:

pls help me with this problem

1) Container A contains 250 red marbles and 200 blue marbles. Container B contains 600 red marbles and 150 blue marbles.How many red and blue marbles must be moved from Container A to Container B such that 25% of the marbles in Container A are red and 75% of the marbles in container B are red.

Red : 250 + 600 = 850
Blue : 200 + 150 = 350

25%A + 75%B = 850 ------------- (1)
75%A + 25%B = 350 -------------(2)

100%A + 100%B = 1200 ------------(1) + (2)
100%A + 300%B = 3400 -------------(1) X 4
200%B = 3400 – 1200 = 2200
100%B = 1100
100%A = 100

No. of red and blue marbles transferred from Container A to B
= (250 + 200) – 100 = 350