Tutor MathsGuru: Ask me for your burning Maths questions!

[laikiasu]

Hi Mathsgurus out there,


Qn: Mrs Ong owns 3 dogs. Each dog gave birth to 3 puppies and when the puppies grew up, they each gave birth to 3 puppies. How many dogs does Mrs Ong own now?
Ans: 18 (found in answer page) but my own answer was 39.

Can you help tell me how to get 18? Or is there a printing error in the answer page?

Thanks.

Rgds,
laikiasu

[Muffins]

laikiasu:

Hi Mathsgurus out there,


Qn: Mrs Ong owns 3 dogs. Each dog gave birth to 3 puppies and when the puppies grew up, they each gave birth to 3 puppies. How many dogs does Mrs Ong own now?
Ans: 18 (found in answer page) but my own answer was 39.

Can you help tell me how to get 18? Or is there a printing error in the answer page?

Thanks.

Rgds,
laikiasu

Hi laikiasu, I think you got 39 by this method, right?

3 x 3 = 9
9 x 3 = 27
9 + 3 + 27 = 39

It is the correct answer. 18 is wrong...

[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.


Hi Mathsguru,
pls help me this ques:
1. There were a total of 2244 men and women in the hall. 1/3 of the men is equal to 5/7 of the women.
a) how many men were in the hall?
b) how many more men than women were in the hall ?

Thanks


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.

[laikiasu]

Thank you Muffins!

Yup that's how I worked out the answer. I doubted myself cos all the other answers in the exercise were correct except this one...hee.

:celebrate: Cheers!

[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…

[Yu Xuan]

1. There were a total of 2244 men and women in the hall. 1/3 of the men is equal to 5/7 of the women.

a) how many men were in the hall?
b) how many more men than women were in the hall ?


Let me try…

To start off, make the numerator of both fractions equal and the denominators will represent the total units for men and women respectively.

Men –> 1/3 = 5/15
Women –> 5/7
Total –> 7 units + 15 units = 22 units

Part (a)
22 units –> 2244
15 units –> 2244/22 * 15 = 1530

Part (b)
15 units - 7 units = 8 units
8 units –> 2244/22 * 8 = 816

[Ngserene617]

Yu Xuan:

1. There were a total of 2244 men and women in the hall. 1/3 of the men is equal to 5/7 of the women.

a) how many men were in the hall?
b) how many more men than women were in the hall ?


Let me try...

To start off, make the numerator of both fractions equal and the denominators will represent the total units for men and women respectively.

Men --> 1/3 = 5/15
Women --> 5/7
Total --> 7 units + 15 units = 22 units

Part (a)
22 units --> 2244
15 units --> 2244/22 * 15 = 1530

Part (b)
15 units - 7 units = 8 units
8 units --> 2244/22 * 8 = 816

Thank you , Yu Xuan

[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

[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?