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
Hi may I ask where are the answers for 23 and 25?
ReplyDeleteHi I if I score 9/25 what can I get?
ReplyDeleteWhy isn't q18 2019?
ReplyDeletetry k=3
Deleteshould question 13 be 20*15*17 instead of 20*16*16 because an arithmetic progression needs to have the common ratio different from 0
ReplyDeleteCan 4/25 get HM?
ReplyDeleteshould question 13 be 20*15*17 instead of 20*16*16 because an arithmetic progression needs to have the common ratio different from 0
ReplyDeleteto 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...
ReplyDeleteGot 1qn right
ReplyDeleteI think qn 22 is not 165......
ReplyDeleteYou 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.
ReplyDeleteShouldn't qn 16 be 13? I got p>12, so the smallest positive value of p is 13。
ReplyDeleteI also got 13
DeleteShouldn't the answer for qn1 be 2020 instead of 0??
ReplyDeleteThere is 2 roots 2020 and - 2020 so when u add them together it becomes 0.
DeleteThere is another root 1/2020 and -1/2020 but this cancels out too
DeleteFor qn16, p >= 12. When p = 12, z = 2x, sub in those values will give an infinite no of solutions for y
ReplyDeleteFor 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?
ReplyDeleteoops pls ignore this i was very careless
DeleteU find the length of each side, then u find it is an right angle triangle
Deleteisnt qn16’s answer 13?
ReplyDeleteI got 15 out of 25. Will I get a gold or a silver?
ReplyDeleteI got 8/25 but could have gotten 10/25 bec of carelessness. What can I get with this score?
ReplyDeleteEstimated cut offs for bronze, silver and gold?
ReplyDeleteThis comment has been removed by the author.
ReplyDeleteCan 10/ 25 get me a bronze?
ReplyDeletewhat was the comment that got deleted?
ReplyDeleteI got 15 out of 25. Will I get a gold or a silver?
ReplyDeleteI think you will get silver, but there is also a chance that you get gold.
I wish you all the best.
Any idea what is the cut off for open this year? Higher or lower than last year?
ReplyDeleteInsider information:
ReplyDeleteHM - >6
Bronze - >10
Silver - >13
Gold - >16
The comment that I deleted was just me miscounting my score
ReplyDeleteHi, can I ask is there a chance 9 gets me Silver?
ReplyDeleteWill 12 get me sliver?
ReplyDeletei dont understand why q12 is 1010, shouldnt it be 2020?
ReplyDeleteExpected cutoffs:
ReplyDeleteGold >20
Silver>14
Bronze>10
HM > 5
can 9 get me a bronze
ReplyDeleteq12: put a -1 in (1,2),(3,4), etc till (2019,2020). you only need one -1 for every two rows and columns
ReplyDeleteCan someone explain q23 pls?
ReplyDeleteQ23
ReplyDeletemax 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?
ReplyDeleteI need help wif qn 7
ReplyDeletecan 23/25 get into smo junior team?
ReplyDeletecan13getsilver？
ReplyDeleteare results out
ReplyDeletealao wonderԾ‸Ծ
DeleteAnyone knows the cut off?
ReplyDeleteI think cutoff for gold is 15 as I got gold and my friend who got 14 got silver
ReplyDeletethank u！！
DeleteCUTOFFS FOR SMO OPEN 2020:
ReplyDeleteGold: 15
Silver: 11
Bronze: 8
HM: 6
Information from mathematics teacher
Cutoffs are identical to that for SMO OPEN 2019 (with round 2)
Comments on Q7:
ReplyDeleteSet a = b, f(0) = 0. Set a = -b, f(-a) = -f(a). Replace b with -b, (f(a)-f(b))/(a-b) = f(a^2-b^2)/(a^2-b^2). Let b approach a, then the LHS becomes f'(a) whereas the RHS approaches some constant independently of the choice of a, i.e. f is linear.
I would like to see a more elegant proof on the linearity of f though.
yes! I got full marks again
ReplyDeleteanyone can tell me how to do question 21
ReplyDelete