SMO 2020 Open Questions

SMO 2020 (Open Section) Answers

1. 0

2. 2030

3. 12

4. 27

5. 70

6. 945

7. 50

8. 4

9. 43

10. 8

11. 4097

12. 1010

13. 5120

14. 0

15. 4039

16. 12

17. 8800

18. 2017

19. 41

20. 140

21. 704

22. 165

23. 838

24. 1600

25. 290

## 40 comments:

Hi may I ask where are the answers for 23 and 25?

Hi I if I score 9/25 what can I get?

Why isn't q18 2019?

try k=3

should question 13 be 20*15*17 instead of 20*16*16 because an arithmetic progression needs to have the common ratio different from 0

Can 4/25 get HM?

should question 13 be 20*15*17 instead of 20*16*16 because an arithmetic progression needs to have the common ratio different from 0

to the person who said this, AP does not need to have non-zero common difference. 1,1,1,1,1,... is in AP

I got 2 for qn 14 though...

Got 1qn right

I think qn 22 is not 165......

You should also consider the situation when r=0, this leads to another 55 n (11 chose 2)

so in total there's 165+55 = 210 n before 2020......

2020 in binary is 11111100100 with 11 digits. 11C3 already takes into account r=0.

Shouldn't qn 16 be 13? I got p>12, so the smallest positive value of p is 13。

Shouldn't the answer for qn1 be 2020 instead of 0??

For qn16, p >= 12. When p = 12, z = 2x, sub in those values will give an infinite no of solutions for y

For qn1, if x is a root then -x is also a root

for q6, i got my points of intersection between the lines as (7,4,4), (1,2,3) and (4,5,6), which leads to my area being 12 but this won't give me the answer.. could anyone help me with where i might've gone wrong?

isnt qn16’s answer 13?

oops pls ignore this i was very careless

I got

15 out of 25. Will I get agoldor asilver?I got 8/25 but could have gotten 10/25 bec of carelessness. What can I get with this score?

Estimated cut offs for bronze, silver and gold?

I also got 13

Can 10/ 25 get me a bronze?

what was the comment that got deleted?I got 15 out of 25. Will I get a gold or a silver?I think you

willgetsilver, but thereis also a chancethat you getgold.I wish you

all the best.Any idea what is the cut off for open this year? Higher or lower than last year?

Insider information:

HM - >6

Bronze - >10

Silver - >13

Gold - >16

The comment that I deleted was just me miscounting my score

Hi, can I ask is there a chance 9 gets me Silver?

There is 2 roots 2020 and - 2020 so when u add them together it becomes 0.

Will 12 get me sliver?

i dont understand why q12 is 1010, shouldnt it be 2020?

Expected cutoffs:

Gold >20

Silver>14

Bronze>10

HM > 5

can 9 get me a bronze

q12: put a -1 in (1,2),(3,4), etc till (2019,2020). you only need one -1 for every

tworows and columnsCan someone explain q23 pls?

Q23

max S = floor(n^2/4), min S = n - 1

Guess that everything in between is possible, then solve for n

hello, can someone explain Q15?

I need help wif qn 7

can 23/25 get into smo junior team?

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