Tutor MathsGuru: Ask me for your burning Maths questions!

[YLH88]

Hi,


I need help in solving the below question. Is from Henry Park 2010 P6 prelim paper 2 qn 11

The figure shows an empty tank. It is made from two containers.
The containers are in the form of 2 cubes of sides 8 cm and 20 cm respectively.
The small container is attached to the centre of one of the sides of the big container.
4 litres of water is poured into the big container such that water flows in to fill part of the small container.
What is the height of the water level in the big container ?
Round off your answer to two decimal places.

http://www.postimage.org/image.php?v=TsFkdJ9

Thank you so much!

[MOE Hater]

(20-8)cm/2 = 6cm


6cm x 20cm x 20cm = 2400cm3 (cubic centimetre)

4 litres = 4000cm3

4000cm3 - 2400cm3 = 1600cm3

1cm x 8cm x 8cm + 1cm x 20cm x 20cm = 464cm3

(1600cm3 / 464cm3/cm) + 6cm = 9.45cm (correct to 2 d.p.)

[beauty queen]

Please help me with these questions (pictures attached) Is question 3


(y+7)/12 or (12y+7)/12


http://www.postimage.org/image.php?v=TsFVmp9



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



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

[snowman.022851697]

I'm now at centrepoint and browsing using my phone so i can only do the 3rd question...


If one is n[/n] years old, to calculate the age in months, multiply [i]n by 12, reason being that there are 12 months in a year and that months have a smaller value than years. Therefore in your case it would be y x12 = 12y months old. Then to find the answer, b/c the 7 is in months, just add 7. But you cant put 19y because yoi dont know what y is.

Remember brackets! Answer will be (12y +7) months

and

NOT 12y +7 Months. If the latter were to be the answer the 12y could represent something different altogether. such as seconds, minutes, weeks etc. So a bracket is important as it tells you we need to add the numbers first then put in the unit

Hope i've helped(:

Up to this point, it's still okay. However the answer requires YEARS, so like in the previous example, you multiply to get mths, so you divide 12 to get the number of years.

so, [(12y +7)/12] = answer, which i choose to simplify so you get (y +7/12) years. Not forgetting the brackets though!

[elkniwt]

Hi beauty queen,


For Q1)
After 3 hours, B has 1/2 the journey remaining while A has 2/3 of the journey remaining.

1/2 B = 2/3 A
B / A = 2/3 x 2 = 4/3
Thus B:A = 4:3

For Q2)
A:B:C = 3:4:10 = 9:12:30 (x3)
Since 1/3 B is shaded, 1/3 x 12 = 4 units (i.e. 4 units shaded)
Unshaded units = 30 - 4 = 26
Shaded : Unshaded = 4:26 = 2:13

Regards

beauty queen:

Please help me with these questions (pictures attached)

http://www.postimage.org/image.php?v=TsFVmp9

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

[Herbie]

Hi Vc, wrt the RV qn 17 on candle A n B, i hv looked at uncle tianzhu model on james ang post but i still can’t figure out how to do the RV QN can help to post the solution? Tx

[Vanilla Cake]

firebird:

Dear Vanilla cake


Good afternoon.

Thank you very much for your solution for Henry Park Q18 paper 2, SA 2010 question.

With best regards
Firebird

Dear Firebird,

As school reopens tomorrow, I will be busy preparing for my year 2 (Sec 2) EOY exam. Hope that you are able to understand my solution posted earlier this morning.
As an alternative, pls refer to http://psle2010a.blogspot.com/2010/09/12-x-2-x-pi-x-18-56.html.His solution is different from mine but the end result is the same.

Wish your son all the best in next Friday's PSLE 2010 LC exam and the upcoming PSLE 2010 written exams.

[Vanilla Cake]

Herbie:

Hi Vc, wrt the RV qn 17 on candle A n B, i hv looked at uncle tianzhu model on james ang post but i still can't figure out how to do the RV QN can help to post the solution? Tx

Hi Herbie,

As school reopens tomorrow, I will be busy preparing for my year 2 (Sec 2) EOY exam.
Pls kindly refer to http://psle2010a.blogspot.com/2010/09/rvps-p6-prelim-2010-p2-q17.html which I believe are clear and well explained.

Question 17
Candle A and candle B are of the same length. Candle A, which is broader, can burn for 5 h while Candle B, the thinner candle, can burn for 4 h. If both candles are lighted at the same time, how long does it take for Candle A to be twice as long left as Candle B?

My suggested solution
Using algebra :

Assume the number of hours burnt be n
1 on the left side is 5/5 and 1 on the right hand side is 4/4

1-n/5=2(1-n/4)
1-n/5=2-n/2
(5-n)/5=(4-n)/2
2(5-n)=5(4-n)
10-2n=20-5n
3n=10
n= 3⅓ hours

It takes 3⅓ hours for Candle A to be twice as long left as Candle B.

Hope that my solution does not cause more confusion for you.

[YLH88]

MOE Hater:

(20-8)cm/2 = 6cm


6cm x 20cm x 20cm = 2400cm3 (cubic centimetre)

4 litres = 4000cm3

4000cm3 - 2400cm3 = 1600cm3

1cm x 8cm x 8cm + 1cm x 20cm x 20cm = 464cm3

(1600cm3 / 464cm3/cm) + 6cm = 9.45cm (correct to 2 d.p.)

Hi MOE Hater,

Thank you for the solution.

[YLH88]

Vanilla Cake:

firebird:

Dear Vanilla cake


Good afternoon.

Thank you very much for your solution for Henry Park Q18 paper 2, SA 2010 question.

With best regards
Firebird

Dear Firebird,

As school reopens tomorrow, I will be busy preparing for my year 2 (Sec 2) EOY exam. Hope that you are able to understand my solution posted earlier this morning.

Hi Vanilla Cake,

All the best to your year 2 EOY exam