Stats - Formulas to learn

Question 1

Answer 1

Question 2

Answer 2

Question 3

Answer 3

Question 4

variance (no frequency)

Answer 4

Question 5

variance (with frequency)

Answer 5

Question 6

frequency density

Answer 6

Frequency/ class width

Question 7

quartiles for listed data

Answer 7

n + 1 and then divide, if a decimal like 2.5 then take the mean of the 2nd and 3rd values

Question 8

quartiles for grouped data

Answer 8

n/4, n/2, 3n/4 ( use linear interpolation)

Question 9

mean of coded data when y = ax + b

Answer 9

both sums and multiplication affect it

Question 10

standard deviation of coded data when y = ax + b

Answer 10

only multiplications affect it

Question 11

Addition rule probability

Answer 11

Question 12

2 formulas for independent events

Answer 12

Question 13

2 formulas for mutually exclusive events

Answer 13

Question 14

conditional probability formula

Answer 14

Question 15

Expected value of a discrete random variable

Answer 15

Question 16

variance of a discrete random variable

Answer 16

Question 17

linear transformation Y= aX + b for the expected value and variance of a discrete random variable w

Answer 17

Question 18

Mean for a discrete uniform distribution with n equally likely outcomes

Answer 18

Question 19

Answer 19

the distribution is symmetrical

Question 20

Answer 20

the distribution has a positive skew

Question 21

Answer 21

the distribution has a negative skew

Question 22

you can model X with a binomial distribution B(n,p) if

Answer 22

• fixed number of trials n
• 2 possible outcomes for X (succes/failure)
• fixed probability of succes p
• trials are independent of each other

Question 23

In order for a Poisson distribution to be a good model, the events must occur :

Answer 23

• independently
• singly in space or time
• at a constant average rate