Tutor MathsGuru: Ask me for your burning Maths questions!

[Tang]

Almighty:

Thank you Tang.This is a new one i learnt 2day.This concept was not known 2 me until now.Thank you to all.

Always compare apple to apple.

[RedRedWine]

Hi Maths Guru


I have 2 questions from Catholic High Prelim exan 2. Can you help tp solve?

1) At a swimmimg pool, the number of boys to the numbers of girls was 4:3. After 3/8 of the boys left and 12 more girls joined the group, there were 2/3 as many boys as girls. How many children were there at the swimming pool first?

2) Tom had $144 more than Ali at first. After Tom spent 25% of his money and Ali spent 1/3 of his money. Tom had $122 more than Ali. How much did Tom have at first?

TIA

[MOE Hater]

RedRedWine:

Hi Maths Guru


I have 2 questions from Catholic High Prelim exan 2. Can you help tp solve?

1) At a swimmimg pool, the number of boys to the numbers of girls was 4:3. After 3/8 of the boys left and 12 more girls joined the group, there were 2/3 as many boys as girls. How many children were there at the swimming pool first?

2) Tom had $144 more than Ali at first. After Tom spent 25% of his money and Ali spent 1/3 of his money. Tom had $122 more than Ali. How much did Tom have at first?

TIA

1) At First - Boys : Girls = 4 : 3 = 16 : 12
After Boys Left - Boys : Girls = 5/8 x 16 : 12 = 10 : 12
After Girls Joined - Boys : Girls = 10 : 3/2 x 10 = 10 : 15
(15-12)u = 3u = 12
1u = 12/3 = 4
(16+12)u = 28u = 4 x 28 = 112

2) Let x be the money Tom had at first

(1-25/100)x = (1-1/3)(x-144) + 122
3/4 x = 2/3 x - 96 + 122
9/12 x = 8/12 x + 26
1/12 x = 26
x = 312

Hope this is self-explanatory enough. :lol:

[abc_parent]

Hi MOE HAter, VanillaCake & Maths Monster

Thanks for your help.

Vanilla Cake, I have indicated the exam paper name in my Subject already, thanks for your pointer, though!

[Vanilla Cake]

Tang:

Almighty:

Thank you Tang.This is a new one i learnt 2day.This concept was not known 2 me until now.Thank you to all.

Always compare apple to apple.

Hi Tang,
Thks for helping to explain to Almighty.

[Vanilla Cake]

abc_parent:

Hi MOE HAter, VanillaCake & Maths Monster

Thanks for your help.

Vanilla Cake, I have indicated the exam paper name in my Subject already, thanks for your pointer, though!

Hi abc_parent,
Refer to your http://www.kiasuparents.com/kiasu/forum/viewtopic.php?t=6373&postdays=0&postorder=asc&start=1380 dated 03 Jun 2010 14:58, you wrote: Post subject: RGPS SA1 2010.In actual fact, it should be RGPS P6 SA1 2009.

[Dharma]

RedRedWine:

Hi Maths Guru


I have 2 questions from Catholic High Prelim exan 2. Can you help tp solve?

1) At a swimmimg pool, the number of boys to the numbers of girls was 4:3. After 3/8 of the boys left and 12 more girls joined the group, there were 2/3 as many boys as girls. How many children were there at the swimming pool first?

TIA

Boys : Girls = 4 : 3 = 16 : 12
Boys : 16u - 6u = 10u
Girls : 12u +12

12u + 12 = 15u
3u = 12
1u = 4
No.of children at first = 28u = 28 x 4 = 112

[Muffins]

RedRedWine:

Hi Maths Guru


I have 2 questions from Catholic High Prelim exan 2. Can you help tp solve?

1) At a swimmimg pool, the number of boys to the numbers of girls was 4:3. After 3/8 of the boys left and 12 more girls joined the group, there were 2/3 as many boys as girls. How many children were there at the swimming pool first?

2) Tom had $144 more than Ali at first. After Tom spent 25% of his money and Ali spent 1/3 of his money. Tom had $122 more than Ali. How much did Tom have at first?

TIA

Hi, we can go about the question like this:

Firstly, change the ratio of boys to girls to a number that is a multiple of 8, in this case 8 itself. It should look like this:

B : G
8 : 6

When 3/8 of the boys left, 5/8 of them left, so we put it as 5 units (u) in this case. The full ratio should look like this:

B : G
8 : 6
(-3u) (+ 12 girls)
5 : 7.5

(7.5 units because 5 divided by 2/3 is 7.5)

7.5u - 6u = 1.5u

1.5 u => 12
1u => 8
8 X (8+6) = 112

[MOE Hater]

Vanilla Cake:

abc_parent:

Hi MOE HAter, VanillaCake & Maths Monster

Thanks for your help.

Vanilla Cake, I have indicated the exam paper name in my Subject already, thanks for your pointer, though!

Hi abc_parent,
Refer to your http://www.kiasuparents.com/kiasu/forum/viewtopic.php?t=6373&postdays=0&postorder=asc&start=1380 dated 03 Jun 2010 14:58, you wrote: Post subject: RGPS SA1 2010.In actual fact, it should be RGPS P6 SA1 2009.

That confused me as well. I study in Henry Park but my teacher got her hands on the RGPS SA1 2010 paper. I completely did not understand when you said questions 13b, 14 and 15 were about circles when none were. As a matter of fact, there was no question 13b

[Vanilla Cake]

MOE Hater:

That confused me as well. I study in Henry Park but my teacher got her hands on the RGPS SA1 2010 paper. I completely did not understand when you said questions 13b, 14 and 15 were about circles when none were. As a matter of fact, there was no question 13b

Hi MOE Hater,
What I mean is that the marble question (answer=350) was from RGPS P6 SA1 2009 Paper 2 Q18. Do you have copies of the RGPS SA1 2010 paper? Perhaps you may wish to post Q13b, 14 and 15 on behalf of abc_parent and provide solutions for them since you mentioned that your teacher got her hands on these papers.Hope this will clear the confusion.