Tagged Questions
0
votes
0answers
26 views
Calculating the probabilities of different lengths of repetitions of numbers of length 6
This question is similar to the question I asked here: Calculating the probabilities of different lengths of repetitions of numbers of length 4
except now I'm having problem with numbers of length 6.
...
1
vote
2answers
32 views
Number of length-five words
How many length-five words can be written using two A's, two T's and one E?
Why is it not $\binom5 2 \times\binom 5 2 \times \binom 5 1$?
Is it $ \binom 5 3 = 10$?
3
votes
2answers
32 views
Number of Strings with two specific letters
How many ways can you construct a string four letters (from 26 alphabet characters) that have both the letters j and k in them?
1
vote
2answers
31 views
Is my answer to this combinatorics question correct? Counting the number of functions where $F(a) = F(b)$?
Let $A = \{a, b, c, d, e, f\}$ and $B = \{1, 2, 3, 4, 5\}$. How many functions $F$ from $A$ to $B$ are there such that $F(a) = F(b)$.
I looked at it like this:
If $F(a)$ and $F(b)$ are equal, that ...
2
votes
1answer
57 views
Is this a Permutation or a Combination?
To win a lottery, you must pick the winning 3 numbers from the integers 1-9 (no repeat numbers). What is the probability of winning the lottery by choosing the correct 3 numbers?
I think its a ...
1
vote
2answers
294 views
Combinatorics and Probability Problem
The problem I am working on is:
An ATM personal identification number (PIN) consists of four digits, each a 0, 1, 2, . . . 8, or 9, in succession.
a.How many different possible PINs are there if ...
0
votes
1answer
37 views
Probability of A Specific Type of Experiment Occuring
The problem is:
An experimenter is studying the effects of temperature, pres-sure, and type of catalyst on yield from a certain chemical reaction. Three different temperatures, four different ...
8
votes
3answers
297 views
How would I figure out how many anagrams of mississippi don't contain the word psi?
I'm really confused how I'd calculate this. I know it's the number of permutations of mississippi minus the number of permutations that contain psi, but considering there's repetitions of those ...
3
votes
1answer
51 views
I don't think I'm doing this function mapping question correctly, could anyone offer advice?
We were given the following question in class:
...
1
vote
2answers
44 views
How would I determine the number of solutions for the sum of this number?
We're given the following equation:
$$x_1 + x_2 + x_3 + x_4 + x_5 = 20$$
I know that the simple amount of solutions to this is $\binom{5+20-1}{5-1}$, but for the following questions I'm slightly ...
1
vote
1answer
30 views
How would I go about solving this statistics question on permutations?
Columba has two dozen each of n different coloured beads. If she can
select 20 beads (with repetition of colors allowed) in 230,230 ways,
what is the value of n?
I'm trying to figure it out, ...
1
vote
1answer
116 views
How do I find the number of bit strings with 3 consecutive 0s in a bit string of length n?
Say n is 8.
How would I ever solve this problem? I've Googled around and searched this site but I haven't come up with much. I'm not even looking for the answer necessarily, just the process by ...
1
vote
2answers
400 views
How to calculate the expected frequency of a pattern?
I'm working on a problem to find the expected frequency of a pattern.
Say there is a sequence of alphabets - A, B, C and D.
The sequence is:
ABDACDBADA.
I want to find the expected frequency of a ...
2
votes
0answers
228 views
sum with permutations
Let $a$ be vector in $R^{2m}$. And let $S_{2m}$ be group of all permutations on the set $\{1,\dots,2m\}$.
I would like to calculate
$$
\sup_{\pi\in S_{2m}}\sum_{d(\sigma, ...
4
votes
1answer
264 views
question involving Markov chain
Let $S_{2m}$ be the group of all permutations $\pi$ of $\{1, 2, \ldots, 2m\}$. The following transition kernel $S$ generates the random transposition walk
$$
Ch(\pi, \pi')= \begin{cases}
\frac{1}{2m} ...
0
votes
1answer
753 views
Combinations and Permutations Question
I am sitting my A level exams (MEI) and I was looking through the S1 past papers and I encountered this question in the January 2010 paper:
Three prizes, one for English, one for French and one ...
