Tutor MathsGuru: Ask me for your burning Maths questions!

[Vanilla Cake]

Ler:

Maha Bohi SA2 math 2010, Paper 2

Many thanks for working out most of the solutions. I hv problem understanding but still trying to work out.

Quick one as I need to go to school,my mum will continue for the rest of your problem sums.

Ler:

Question 7 - In the diagram show above, O is the centre of the circle and OAB is a right angle triange. Given that AB is 10cm and the shaded parts of the circle add up to 133 m square. Find the area of the circle.

Pls post the diagram otherwise how can others be expected to solve without reading the diagram? I notice that you have changed your question as the original question stated \"AB is 10m\" and the diagram showed length of AB labeled as 10m. The original question also stated 133 m² and this is where the confusion comes.So, I change all metres and metres square to cm and cm² to make life simple.

Square of length of AO+Square of length of OB=10cmx10cm (http://en.wikipedia.org/wiki/Pythagorean_theorem)
but length of AO=length of OB (radii of circle)
Assume length of AO be n, so
n²+n²=100
2n²=100
n²=50

Area of triangle AOB = 1/2xABxOB=1/2xn²=1/2x50=25 cm²
Since area of the shaded part of the circle was given as 133 cm², area of the circle = (25+133) cm² = 158 cm².

Need to go now and mum will continue the rest.

[Vanilla Cake]

Ler:

Questions 10. Joanne and Tomomi bought the same bag from the same shop when they went shopping together . Johanne spents 75% of her money on the bag and Tomomi spent 2/3 of hers. What percentage of their total sum of money was the cost of a bag if the girls had $100 left altogether? (round off your answer to the nearest tenth).

75% = 3/4

At first
Joanne: 4u
Tomomi: 3p

Spent (cost of a bag)
Joanne: 3u
Tomomi: 2p

Left
Joanne: u
Tomomi: p

Left -> $100 (given)
u+p = 100

Joanne and Tomomi bought the same bag means spending by both girls were the same -> 3u=2p

Since 3u = 2p,
u+p =100 can be rewritten as 3u+3p=300

2p+3p=300
5p=300
p= 60
u = 100-60=40

Total sum of money -> 4u+3p = 4(40)+3(60)= $340
Cost of a bag = 3u or 2p -> 3(40) or 2(60) = $120 in both cases.
Percentage of the total sum of money that was the cots of a bag = 120/340x100% = 35.3% (nearest tenth)

Ler:

Questions 12. Talik was given some pocket for recess, He realised that if he had spent $0.80 on each meal, he would have 8 meals fewer than if he had spent $0.60 on 8 meals and spent $0.80 on the remaining meals. How many meals did the money last him?

Pls refer to http://psle2010a.blogspot.com/2010/09/decimal-p6-2010-sa2-maha-bodhi-p2-q12.html.
Here's one using algebra:

Assume the number of meals be n if Talik had spent $0.80 on each meal.
$0.80xn = $0.60x( n+8 )
0.8n=0.6n+4.8
0.2n=48
n=24

So, total pocket money = 24x$0.80 = $19.20
Number of remaining meals -> [$19.20-(8x$0.60)]÷$0.80=$14.40÷$0.80=18
18+8=26
The money lasted him for 26 meals.

Ler:

Q14.The diagram above, not drawn to scale, shows the dimensions of wheels of Kens bicycle. he pushed his bicycle down a slope 3m long. How many complete revolutions did the wheel make?
(sorry cant diagram)

It's difficult for KSP readers to solve this question without seeing the diagram, anyway here's my suggested solution:

Radius of wheel = 3+9+(6÷2)=3+9+3=15 cm
Diameter = 30 cm
Circumference = 3.14x30=94.2 cm = 0.942 m
Number of revolutions = 3÷0.942 = 3.184713.... which was 3 complete revolutions.

Note: Question states that pi = 3.14

VC's mum

[Vanilla Cake]

Ler:

Hi mathguru or hi all

I am poor in math, can somebody help me to answer
Maha Bohdhi SA2 Paper 1 (2010)

You need to post the complete questions with diagrams and given answers (Don't worry if they are 100% correct or not) to allow other KSP members to help you.

Ler:

Question 25, For every $2 that I get ...

Ratio of school pocket money
I : My sister
2 : 2+1
2 : 3

Mother gives us $30,
2u+3u=5u
5u = $30
3u = $30÷5x3=$18

My sister gets $18

Ler:

Question 26, The figure above of 4 idential cirlces....

This one is not easy to explain without a diagram.Look at the question again and you will see that each circle has 7 units since it stated that 2/7 of each circle overlaps the one before.
Fill in the units in the diagram from left to right and you will get :
(5+2+3+2+3+2+5)units = 22 units which is the whole figure that consists of 4 identical circles.
Fraction of the figure that is one circle = 7/22

Ler:

Questions 27, During a science experiment....

This one is also difficult to explain without a diagram.
OK, look at the question again and you will see that:

1 litre = 1000 ml
0.75 litre = 750 ml

Beaker A: (1000ml÷10)x1= 100 ml
Beaker B: (500ml÷10)x7=350 ml
Beaker (750ml÷10)x3=225 ml

Beaker (A+B+C) = (100+350+225)ml = 675 ml

Beaker C is a 0.75l = 750 ml with intervals of 10 divisions.Each division = 75 ml
675 ml ÷ 75 ml = 9
So, the water level must be at the 9th marking of beaker C to show that the amount of water is 675 ml.

VC's mum

[Vanilla Cake]

Ler:

Questions 28, ABC and PQR.......

This question comes with a diagram. Read carefully and look for the clues to solve this question.

Assume the length of XY be n.
Length of BR = 20 cm (Given) = 4+n+1+n+1+4=20
since BQ=CR=4 cm and QY=YC (Difficult to explain through online as many words are required to type).

4+n+1+n+1+4=20
2n+10=20
2n=10
n=5

QC=n+1+n+1=2n+2 = 2(5)+2=12 cm
XY = n= 5 cm
Area of triangle XQC = 1/2xQCxXY = 1/2x12x5=30 cm²

Ler:

Question 29, In the diagram....

This comes with diagram again.
From the diagram and info given, you can see that both OJ,OK and OL are radii of the circle since O is the centre of the circle.
Since angle LJK = 35⁰ then angle OKJ =35⁰ (Triangle OJK is isosceles)
Angle KOL=35⁰+35⁰=70⁰ (sum of 2 int angles = 1 ext angle)
Angle OKL = Angle OLK = (180⁰-70⁰)÷2=55⁰ (sum of angles in a triangle)
Angle OLM = 180⁰-55⁰ = 125⁰ (Angles on a straight line)

VC's mum

[Dharma]

Ler:

Maha Bohi SA2 math 2010, Paper 2


Questions 10. Joanne and Tomomi bought the same bag from the same shop when they went shopping together . Johanne spents 75% of her money on the bag and Tomomi spent 2/3 of hers. What percentage of their total sum of money was the cost of a bag if the girls had $100 left altogether? (round off your answer to the nearest tenth).

Joanne => ¾ of her money
Tomomi => 2/3 of her money

¾ of Joanne = 2/3 of Tomomi
6/8 of Joanne = 6/9 of Tomomi

% of cost of 1 bag compared to total sum of money = 6/17 x 100% = 35.3% (rounded to nearest tenth)

[Vanilla Cake]

Ler:

Question 30, After 40% of the boys....

OK, last question from you. BTW, are you a parent and is your child taking PSLE 2010 exam?My DD2 will be taking PSLE exam next year (2011).
Using unit and part method,

Before
Boys : Girls
u : p

Change
40% of the boys had been promoted and there were as many boys as girls left.........

60% of the boys left and no change for the girls.

After
Boys: Girls
0.6u : p

Given that p=0.6u, so percentage of the pupils in the club that were girls originally-> p/(u+p)x100%
= 0.6u/(u+0.6u)x100%
= 0.6u/1.6ux100%
= 3/8x100% = 37½%

Ler:

I try to do the math, but i got it wrong. Need???

You may wish to refer to http://prischoolmaths.blogspot.com/ and http://psle2010a.blogspot.com/ for many worked Maths examples by Observer.
Thks.

VC's mum

[Vanilla Cake]

liketoeat:

Hi, I need help with this question. No answer given.


A group of people went hunting. On average, 6 people hunted 5 rabbits, 15 people hunted 2 deer and 10 people hunted 1 buffalo. The total number of animals hunted was 6 more than the total number of people who went hunting. How many people went hunting?

Thank you.

There is answer given for this question. Your question is from http://www.orlesson.org/orp/09Ma/2009-P6-Math-CA1-Rulang.pdf.
Answer is 90 people and Tianzhu and Dharma had solved and posted the solution for this question before in KSP forum.

Tianzhu/Dharma - Pls repost the solution or direct the link for your solution.
Thks

VC's mum

Suggested solution from DD2 (P5)

\"->\" means hunted
6p-> 5r
30p-> 25r
15p-> 2d
30p-> 4d
10p-> 1b
30p-> 3b

Total: 30p, 32 animals
Difference=2
6÷2=3
3x30=90

Answer : 90 people

[Dharma]

Vanilla Cake:

liketoeat:

Hi, I need help with this question. No answer given.


A group of people went hunting. On average, 6 people hunted 5 rabbits, 15 people hunted 2 deer and 10 people hunted 1 buffalo. The total number of animals hunted was 6 more than the total number of people who went hunting. How many people went hunting?

Thank you.

There is answer given for this question. Your question is from http://www.orlesson.org/orp/09Ma/2009-P6-Math-CA1-Rulang.pdf.
Answer is 90 people and Tianzhu and Dharma had solved and posted the solution for this question before in KSP forum.

Tianzhu/Dharma - Pls repost the solution or direct the link for your solution.
Thks

Suggested solution from DD2 (P5)

\"->\" means hunted
6p-> 5r
30p-> 25r
15p-> 2d
30p-> 4d
10p-> 1b
30p-> 3b

Total: 30p, 32 animals
Difference=2
6÷2=3
3x30=90

Answer : 90 people

VC's mum

6 people => 5 rabbits
30 people => 25 rabbits
15 people => 2 deers
30 people => 4 deers
10 people => 1 buffalo
30 people => 3 buffaloes

A group of 30 people can hunt (25 + 4 + 3) = 32 animals
Difference between the no. of animals and people = 32 – 30 = 2

If the difference between the no. of animals and people = 6
No. of people who went hunting = 30 x 3 = 90

[tianzhu]

Vanilla Cake:

liketoeat:

Hi, I need help with this question. No answer given.


A group of people went hunting. On average, 6 people hunted 5 rabbits, 15 people hunted 2 deer and 10 people hunted 1 buffalo. The total number of animals hunted was 6 more than the total number of people who went hunting. How many people went hunting?

Thank you.

There is answer given for this question. Your question is from http://www.orlesson.org/orp/09Ma/2009-P6-Math-CA1-Rulang.pdf.
Answer is 90 people and Tianzhu and Dharma had solved and posted the solution for this question before in KSP forum.

Tianzhu/Dharma - Pls repost the solution or direct the link for your solution.Thks

Hi

Please refer to pg 38 of this thread.
http://www.kiasuparents.com/kiasu/forum/viewtopic.php?t=6373&postdays=0&postorder=asc&start=370

Best wishes

[liketoeat]

Thank you very much to VC’s mum, DD2, Dharma and Tianzhu for your very quick response. Thank you again.