#### Probability & Statistics

in combination, does order matter?

no

in permutation, does order matter?

yes

combination formula

nCr = n!/r!(n-r)!n things, taken r at a time

permutation formula

nPr = n!/(n-r)!n things, taken r at a time

circular permutation is used for ___?

to calculate the number of ways to arrange n objects around a circle

circular permutation formula

(n-1)!where n is number of objects youre trying to arrange in a circle.

what is the probability of rolling two dice and having the two numbers add to 4? approach???

0

how many ways can the letter in IDENTITY be arranged? approach?

0

what is the probability of pulling 3 spades in a deck without replacement? approach?

0

When dealing with an and/or statement, or means _____

When dealing with an and/or statement, and means _____

multiply

standard deviation definition

a measure of variability that describes an average distance of every score from the mean

5 steps to find standard deviation

1. find mean2. subtract the mean from each of the data set values3. square each of those values4. average these values5. square root that

standard deviation formula

sqrt((xn-xav)^2/(n)

variance

the standard deviation squared

z score

the measure of standard deviation

Union (u)

includes all data but excludes duplicate values(u)

intersection (n)

includes only data that exists in both sets

what is the middle box of a box and whisker plot

the middle 50%(interquartile range)

what is the middle line of a box and whisker plot?

the median value

what are the two end points of a box and whisker plot?

the max and min values

1 standard deviation from the mean is _____% of the data

68%

2 standard deviations from the mean is _____% of the data

95%

3 standard deviations from the mean is _____% of the data

99%

if p-value > significance level then you ______ the hypothesis

fail to reject

if p-value < significance level then you ______ the hypothesis

reject

z score is a measure of ______

standard deviation

what does a Z score of 2.5 mean?

2.5 standard deviations away from the mean

p-value

The probability level which forms basis for deciding if results are statistically significant (not due to chance).

when a question asks you to solve for the probability of "at least one", you can just do:

[1-(probability of none)]where x is how many choices you have