(4) discrete probability Flashcards
(9 cards)
- What are random variables and what are they written as?
- What about the particular values?
- What is the range of values a random variable can take?
- What are the way a probability distribution can be presented?
1.-Written as upper case letters X or Y
.-Whose random depends on the outcome of the particular event
- -The particular values that are taken take lower case.
- sample space.
As a diagram, as a table and as a probability mass function.
How do you draw a table for probability distribution?
What is a rule for these tables?
-1st row is little x and the particular values the outcome s can take
2nd row is X=x with the individual probabilities.
The bottom row must sum to one.
What is a probability mass function?
What must be remembered?
- This is X curvy bracket,
- The probabilities that x can take next to what values of x this happens for.
0 for otherwise.
How does the calculator do cumulative binomial distribution?
-It does less than or equaled to
When can you use a normal distribution to approximate a binomial distribution?
-How do you work this out?
- when n is large
- p must be close to 0.5
Formula booklet page 8
What must be remembered during normal approximation?
For example what would you do if you need P(X>25)
-half continuity correction as you are moving from discrete data to continuous data.
25 could be 24.5 or 25.5
so you want P(X>25.5)
What is a refinement to using a uniform distribution for a model?
-Using a non-uniform distribution that can allow cloud cover to vary at different times and different times of the year.
What are the conditions for a binomial distribution?
- Fixed number of trials
- Trials are independent
- Two outcomes success and failure.
On what basis does working out the binomial distribution work?
-nchooser
