Tutor MathsGuru: Ask me for your burning Maths questions!

[Brenda10]

RedRedWine:

Dharma:

[quote=\"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

Thank you MOE Hater, Dharma and Muffins.

[/quote]Hi, my girl would like to give a try. Hopefully her steps and answer are correct.



\t\tB : G\t\t\t\t
\t\t4 : 3\t(At first)\t\t\t
\t\tx 2 : x 2\t(to get the denominator of 8 )
\t\t8 : 6\t\t\t\t
\t-3u : +12\t\t\t\t
\t\t5u : ?\t(This becomes 5u :7.5u aft 10u:15u)
\t\tx2 : x2\t\t\t\t
\t 10u: 15u\t(At the end 2:3)\t\t\t
\t\t\t\t\t\t\t

\t\t7.5u -\t6u\t= 1.5u\t
\t\t12 /\t1.5\t= 8\t

\tTherefore\t8u x\t8\t= 64\t(boy)
\t\t6u x\t8\t= 48\t(girl)

\t\t64 + 48 = 112\t


Answer: There were 112 children at first.

Thank you.

[Muffins]

Hi Brenda10, your daughter just managed to summarise my workings into a few steps! :shock: How old is your DD???

[Brenda10]

Muffins:

Hi Brenda10, your daughter just managed to summarise my workings into a few steps! :shock: How old is your DD???

Thank you Muffins.

She is 11 years old.

[YLH88]

Hi all,


Need help with the following questions :

1) Nan Hua SA1 2009 P1 Qn 14
Adrian and Bob started driving at the same time. Bob took 6 hours to complete his journey while Adrian took 9 hours to complete his. After 3 hours, the two men were left with the same distance to complete. What is the ratio of the distance of Bob's journey to the distance of Adrian's journey ?

a) 1:2
b) 1:3
c) 2:3
d) 4:3


2) Nan Hua SA1 2009 P1 Qn 15
In the figure, not drawn to scale, the ratio of the area of Circle A to Circle B to Circle C is 3 : 4 : 10. If 1/3 of B is shaded, what is the ratio of the shaded part to the unshaded part of the figure ?

a) 1:17
b) 2:13
c) 3: 17
d) 4:13

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

3) AiTong SA1 2009 P2 Qn 15
Tommy and Wilson jog on a hexagon track (6 equal sides) at 8 am. Tommy starts at point C while Wilson starts at point F. Both jog in the direction as shown by the arrows. Tommy's speed is 1.5 times Wilson's.
a) At which point will they meet ?
b) If they meet at 8.20 am, find Tommy's speed ?

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

Thank you so much!

[Brenda10]

YLH88:

Hi all,


Need help with the following questions :




2) Nan Hua SA1 2009 P1 Qn 15
In the figure, not drawn to scale, the ratio of the area of Circle A to Circle B to Circle C is 3 : 4 : 10. If 1/3 of B is shaded, what is the ratio of the shaded part to the unshaded part of the figure ?

a) 1:17
b) 2:13
c) 3: 17
d) 4:13

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

Thank you so much!

Hi, for this question, answer very hight chance should be (b)

A B C

3:4:10
9:12:30 (x3 due to 1/3 of B is shaded)
4 (B shaded = 1/3, use 12/3=4)

Then whole figure 30 - 4 also, get 26

4:26
Then simplified to
2:13

Hopefully this answer is correct.

Thank you.

[MOE Hater]

YLH88:

Hi all,


Need help with the following questions :

1) Nan Hua SA1 2009 P1 Qn 14
Adrian and Bob started driving at the same time. Bob took 6 hours to complete his journey while Adrian took 9 hours to complete his. After 3 hours, the two men were left with the same distance to complete. What is the ratio of the distance of Bob's journey to the distance of Adrian's journey ?

a) 1:2
b) 1:3
c) 2:3
d) 4:3


2) Nan Hua SA1 2009 P1 Qn 15
In the figure, not drawn to scale, the ratio of the area of Circle A to Circle B to Circle C is 3 : 4 : 10. If 1/3 of B is shaded, what is the ratio of the shaded part to the unshaded part of the figure ?

a) 1:17
b) 2:13
c) 3: 17
d) 4:13

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

3) AiTong SA1 2009 P2 Qn 15
Tommy and Wilson jog on a hexagon track (6 equal sides) at 8 am. Tommy starts at point C while Wilson starts at point F. Both jog in the direction as shown by the arrows. Tommy's speed is 1.5 times Wilson's.
a) At which point will they meet ?
b) If they meet at 8.20 am, find Tommy's speed ?

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

Thank you so much!

My teacher has given me the Nan Hua paper and I am pretty sure she wouldn't give P6ers a P1 paper.

[MOE Hater]

KSP:

Just wonder where Mathsguru is. Have not seen her answering questtion for a long time.

Good Point. By the way, how do you know mathguru is a she? Boys tend to be better at Math, I suppose. :roll:

[CoffeeCat]

MOE Hater:

KSP:

Just wonder where Mathsguru is. Have not seen her answering questtion for a long time.

Good Point. By the way, how do you know mathguru is a she? Boys tend to be better at Math, I suppose. :roll:

maybe it's because you were new to this forum or not seen the first page of this thread. Mathsguru mentioned somewhere that she is a she.

[YLH88]

Hi all,


Sorry, to clarify, the below questions are all for P6 level, the P1 and P2 is referring to whether Paper 1 or Paper 2. I have made the amendments for the below. Ya, I too wonder where is Mathsguru .....

Need help with the following questions :

1) Nan Hua P6 SA1 2009 Paper 1 Qn 14
Adrian and Bob started driving at the same time. Bob took 6 hours to complete his journey while Adrian took 9 hours to complete his. After 3 hours, the two men were left with the same distance to complete. What is the ratio of the distance of Bob's journey to the distance of Adrian's journey ?

a) 1:2
b) 1:3
c) 2:3
d) 4:3


2) Nan Hua P6 SA1 2009 Paper 1 Qn 15
In the figure, not drawn to scale, the ratio of the area of Circle A to Circle B to Circle C is 3 : 4 : 10. If 1/3 of B is shaded, what is the ratio of the shaded part to the unshaded part of the figure ?

a) 1:17
b) 2:13
c) 3: 17
d) 4:13

http://www.postimage.org/image.php?v=gxsuNh0


3) AiTong P6 SA1 2009 Paper 2 Qn 15
Tommy and Wilson jog on a hexagon track (6 equal sides) at 8 am. Tommy starts at point C while Wilson starts at point F. Both jog in the direction as shown by the arrows. Tommy's speed is 1.5 times Wilson's.
a) At which point will they meet ?
b) If they meet at 8.20 am, find Tommy's speed ?

http://www.postimage.org/image.php?v=aVD5NPS


Thank you so much!

[YLH88]

[quote]
YLH88 wrote:
Hi all,

Need help with the following questions :




2) Nan Hua SA1 2009 P1 Qn 15
In the figure, not drawn to scale, the ratio of the area of Circle A to Circle B to Circle C is 3 : 4 : 10. If 1/3 of B is shaded, what is the ratio of the shaded part to the unshaded part of the figure ?

a) 1:17
b) 2:13
c) 3: 17
d) 4:13



Thank you so much!


Hi, for this question, answer very hight chance should be (b)

A B C

3:4:10
9:12:30 (x3 due to 1/3 of B is shaded)
4 (B shaded = 1/3, use 12/3=4)

Then whole figure 30 - 4 also, get 26

4:26
Then simplified to
2:13

Hopefully this answer is correct.

Thank you.

[/quote]Hi Brenda10,

I can understand the first part, where
A B C
3:4:10
9:12:30 (x3 due to 1/3 of B is shaded)

But why do you take 30 - 4 ? Your answer is correct (answer in the answer key is b)