can any1 remember what was the binary subset in the 1st question?
then the answers are 1 a) 80
b)192
c=448
n hey what are ur respective classes?
Can anyone who solved the third question post their method? Looks like everyone’s getting different results on that one.
well i did them like that…
let X=11011
so a binary sequence of 9 dig would be of forms
X _ _ _ _
_ X _ _ _
_ _ X _ _
_ _ _ X _
_ _ _ _ X
so this is a case of permutations where repitition is allowed
so the permutations of 0 and 1 in the blanks would be 2^4
as the position of x is independent of position of the permutations of the other binary digits,
the ans is 5*(2^4)=80
can someone post the questions?
I believe your method is wrong. You’re doing some double counting this way. For instance, (11011)0110 is the same as 110(11011)0.
Today’s P3 (King and Minister) was actually INMO 1992 P4 (k=6).
You can check out the discussion on AOPS here.
These are called indecomposable permutations; one can solve for the number of them of a given length using generating functions, or use a recursion. They are given by sequence A003319 in the OEIS.
The answers were:
- 71
- 461
- 3447
1 a. 80 b. 192 c. 448 - ✗
2 a. 40 b. 52 c. 96 - ✓
3 a. 71 b. 461 c. 3447 - ✓
4 a. 13 b. 10 c. 12 - ✓
I think I scored 60, I’m in class 12.
Also, this
Guys what about problem 2?
Great to know I know I got P3 fully correct
What do you reckon the cutoff will be?
I think in the range of 25-35 from 10th to 12th so 25 for 10th and 30 for 11th and 35 for 12th as last year’s was much easier and the cutoff range was 35-45.
when r the results supposed to come out?
1- 75 179 420 (Not sure about the last 2)
2- 24 48 96
3- (Got it wrong)
4- 13 10 12 (Easy one)
Does anyone remember the 1st question(any part) ? I’d like to try solve it again
Well last time they got the results in 10 days so I guess it will be the same this time as well.
Well last time they got the results in 10 days so I guess it will be the same this time as well.
btw this time zio-zco were conducted together and zio was also conducted online so we can expect the result much sooner than that