Tuesday, 8 September 2020

SMO 2020 (Open Section) Answers

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:

Anonymous said...

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

Anonymous said...

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

Anonymous said...

Why isn't q18 2019?

Anonymous said...

try k=3

Anonymous said...

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

Anonymous said...

Can 4/25 get HM?

Anonymous said...

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

Anonymous said...

I got 2 for qn 14 though...

Unknown said...

Got 1qn right

Anonymous said...

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......

Lim Jeck said...

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

Anonymous said...

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

Anonymous said...

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

Anonymous said...

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

Anonymous said...

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?

Anonymous said...

isnt qn16’s answer 13?

Anonymous said...

oops pls ignore this i was very careless

Anonymous said...

I got 15 out of 25. Will I get a gold or a silver?

Anonymous said...

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

h said...

Estimated cut offs for bronze, silver and gold?

Unknown said...

I also got 13

akasht said...
This comment has been removed by the author.
akasht said...

Can 10/ 25 get me a bronze?

Anonymous said...

what was the comment that got deleted?

Anonymous said...

I got 15 out of 25. Will I get a gold or a silver?

I think you will get silver, but there is also a chance that you get gold.

I wish you all the best.

Anonymous said...

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

Anonymous said...

Insider information:

HM - >6
Bronze - >10
Silver - >13
Gold - >16

akasht said...

The comment that I deleted was just me miscounting my score

Anonymous said...

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

Anonymous said...

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

Anonymous said...

Will 12 get me sliver?

Anonymous said...

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

Anonymous said...

Expected cutoffs:

Gold >20

Silver>14

Bronze>10

HM > 5

Anonymous said...

can 9 get me a bronze

Anonymous said...

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

Anonymous said...

Can someone explain q23 pls?

Lim Jeck said...

Q23
max S = floor(n^2/4), min S = n - 1
Guess that everything in between is possible, then solve for n

Anonymous said...

hello, can someone explain Q15?

Anonymous said...

I need help wif qn 7

Anonymous said...

can 23/25 get into smo junior team?