Stats

Question 1

Conditions for a binomial distrubution

Answer 1

• The probability remains constant
• The events are independent
• data is discrete

Question 2

AND

Answer 2

Multiply

Question 3

OR

Answer 3

ADD

Question 4

by default how does a binomial distrubution measure

Answer 4

≤ / ≥

Question 5

P(X less than x)

Answer 5

= P(X ≤ x-1)

Question 6

P(a≤X≤b) =

Answer 6

= P(X ≤ b) - P(x ≤ a-1)

Question 7

P(X≥x)=

Answer 7

= 1- P(X≤x-1)

Question 8

P(X>x)=

Answer 8

= 1 - P(X≤x)

Question 9

Where do points of inflection occur on a normal distribution curve

Answer 9

1 standard deviation from the mean

Question 10

standard variable

Answer 10

z = (x - μ) / σ

Question 11

Normal approximation to binomial test

Answer 11

np>5

nq>5

Question 12

Normal approximation to binomial conditions

Answer 12

n must be large

p must be close to 1/2

Question 13

Normal approximation to the binomial

Answer 13

X ~ N (np, npq)

Question 14

μ+-σ

Answer 14

2/3 or 67%

Question 15

μ+-2σ

Answer 15

95%

Question 16

μ+-3σ

Answer 16

97.7%

Question 17

standard normal distrubution

Answer 17

mean = 0 , standard deviation = 1

Question 18

npq

Answer 18

varience (standard deviation^2)

Question 19

When is stem and leaf good

Answer 19

when representing small amounts of discrete data

Question 20

Outlier =

Answer 20

μ +- 2σ
or
UQ + 3/2 * IQR
LQ - 3/2 * IQR

Question 21

When is the median + IQR better than mean and standard deviation?

Answer 21

when there are outliers.

IQR and Median are not effected by outliers

Question 22

frequency standard deviation

Answer 22

√((Σx²f/Σf) - x̅²)

Question 23

standard deviation

Answer 23

√((Σx²/n) - x̅²)

Question 24

frequency density =

Answer 24

frequency / class width

Question 25

estimating the mean for grouped data

Answer 25

Σx* midpoint / n

Question 26

position of the nth percentile

Answer 26

n/100 * frequency

Question 27

lower class boundary / upper class boundary

Answer 27

if ≤ / ≥ then its the actual value

if < / > then its the value +- 0.5

Question 28

ploting culmulative frequency

Answer 28

always plot upper class boundary

Question 29

P(A∪B) =

Answer 29

P(A) + P(B) - P(A∩B)

Question 30

P(A|B)

Answer 30

P(A∩B) / P(B)

Question 31

P(A∩B) for mutually exclusive

Answer 31

= 0

Question 32

For independent events P(A∩B) =

Answer 32

P(A)P(B)

Question 33

For independent events P(A|B) =

Answer 33

P(A)

Question 34

sum of probabilities in a probability distribution =

Answer 34

1

Question 35

nCr =

Answer 35

n!/r!(n-r)!

Question 36

how many ways can n objects be arranged

Answer 36

n!

Question 37

How many ways can n objects be arranged is r of those objects are the same?

Answer 37

n!/r!

Question 38

For binomial: P(success) =

Answer 38

nCr * P(success)^r * P(failure)^n

Question 39

conditions for a normal distrubution

Answer 39

• data is continous
• data is symmetrically distrubuted with a peak
• data tails off either side of the mean

Question 40

critical value normal hypothesis tests method

Answer 40

critical value = μ +- kσ/√n
k = Ф(sig level)
if observed mean more extreme than critical value then reject H0

Question 41

Normal hypothesis test method

Answer 41

Z = observed - expected / sample standard deviation
k = Ф(sig level)
if Z is more extreme than k reject H0