Yay!

I went for the Hwa Chong Math Quest 2010 yesterday. We (my mother, Lim Li and I) took 3 buses (186, 153, 174) from my house and alighted at HCI's 1st bus stop (there are 3 bus stops that lead to 3 different HCI entrance gates). There was some construction going on and the first gate was closed. So we walked to the 2nd bus stop. Still no open gate in sight. We then took a bus (luckily it's distance-based fare now, so it was free or cost only a few cents) to the 3rd bus stop, and entered HCI through the 3rd gate. The whole HCI was like a ghost town (it's Saturday at 8 am) and there was not a single soul to guide us - no signs on the Math Quest and no Hwa Chong students around to provide direction. It took us quite long to find LT3 (competition venue at 2nd level) as the direction signs to the LTs are not very clear. Fortunately I was not late. My mother and Lim Li then left for the RGS Speech Day and Prize Presentation Ceremony, as Lim Min has won an award.

Yay, NUS High has won the Individual 1st and Team 1st in the Hwa Chong Math Quest. I got a ridiculously huge trophy, a TI Graphic Calculator (my 3rd one, I had 2 from the NJC Math Challenge 2010), a 2 GB TI Thumb Drive and $50 Popular Book Vouchers.

More Photos

These photos were taken by our teachers, Mrs Ng and Ms Lim.

Group photo with our buddies and teachers (Mrs Ng and Ms Lim).

1-Day Excursion on 12 August. We visited 赵州桥 (above) and 大佛寺.

Accessing Internet from the staff room, during our free time.

CGMO Photos

CGMO Opening Ceremony.

Our quad-sharing hostel room in Shijiazhuang No. 2 Middle High School. With the exception of Zhang Aidi who climbed up the upper deck to sleep, the rest of us brought the mattresses down and slept on the floor.

Uniform provided by CGMO organiser, which we had to wear for opening and closing ceremonies.

This building is the library of Shijiazhuang No. 2 Middle High School.

The open concept bathing area. Only the China girls dared to bathe here openly. The girls from the other countries either bathed with T-shirts and shorts, or locked the place when bathing alone, or bathed in the hostel toilet (with buckets of water).

One of the well-decorated classroom walls.

So much wastage, at the closing dinner. After we had our fill, these were the left over dishes.

CGMO Results Out!

This is posted by LJ's mum.

This year's CGMO officially closes today. About 200 students participated, of which 20 are awarded Gold medals, 40 Silver medals and 60 Bronze medals.

The two Singapore teams comprising 8 girls won a total of 5 medals, as follows:
Silver - Aidi
Bronze - Catharine, Lim Min, Jazlene, Pin Lin

Congrats to the girls! It is a marked improvement over last year's haul of 1 Bronze medal.

CGMO 2010

Lim Min has flown to Shanghai early this morning (1.15 am) on SQ826, and she will be taking another flight at 12.50 pm to Shijiazhuang Daguocun. She is part of the RI/RGS team (comprising Catharine, Xin Xuan, Aidi and Lim Min) which is taking part in the China Girls Maths Olympiad held at Shijiazhuang, the capital of Hebei Province, about 40 miles southwest of Beijing. There are 2 teams from Singapore; NUS High is sending the other team of 4 girls.

The programme/itinerary is as follows:
8 Aug (Sun) - Arrival, check-in to Shijiazhuang No. 2 Middle School Student Dormitory
9 Aug (Mon) - Opening ceremony
10 Aug (Tue) - Competition Day 1
11 Aug (Wed) - Competition Day 2
12 Aug (Thu) - Excursion / Closing dinner
13 Aug (Fri) - Closing ceremony / departure to Singapore (arrival at Changi Airport at 12.25 am, 14 Aug)

Wishing both Singapore teams all the best!

NMOS 2010 Special Round Qn 5

Question 5: A company could use any of the 3 builder (Anthony, Bob and Charles) to build a wall. Anthony would take A days to build the wall. Likewise, Bob and Charles would take B days and C days to build the wall respectively.
Anthony and Bob take 16.8 days to complete a wall.
Anthony and Charles take 21 days to complete a wall.
Bob and Charles take 28 days to complete a wall.

Solution:
Anthony builds 1 wall in A days. Hence, Anthony builds 1/A wall in 1 day.
Similarly, Bob builds 1/B wall in 1 day, and Charles builds 1/C wall in 1 day.
In 1 day, Anthony and Bob together will build (1/A + 1/B) wall. In 16.8 days, Anthony and Bob will build [16.8x(1/A + 1/B)] wall which is 1 wall since Anthony and Bob complete the wall in 16.8 days. Hence, we get the following equations:

16.8(1/A + 1/B) = 1
21(1/A + 1/C) = 1
28(1/B + 1/C) = 1
Implying..
1/A + 1/B = 1/16.8 -------- (1)
1/A + 1/C = 1/21 ---------- (2)
1/B + 1/C = 1/28 ---------- (3)

(1)+(2)-(3)
2(1/A) = 1/16.8 + 1/21 - 1/28 = 1/14
Therefore, 1/A = 1/28, hence, A = 28.
From (1), 1/B = 1/16.8 - 1/28 = 1/42. Hence, B = 42.
From (2), 1/C = 1/21 - 1/28 = 1/84. Hence, C = 84.

Answer: A+B+C=154

NMOS 2010 Special Round Answers

1. 20
2. 2
3. 15
4. 216
5. 154
6. 54
7. 25
8. 12
9. 38
10. 75
11. 542
12. 48
13. 108
14. 12
15. 65
16. 24
17. 40
18. 25
19. 4
20. 62

Note: many answers were contributed by Lim Min and Lim Jeck.
Lim Li - if you have different answers and you are sure that you are correct, please let me know.