Statistic Year 2

Question 1

Bivariate

Answer 1

Two variables

Question 2

product moment variable coefficient

Answer 2

gives type (positve or negative) and strength of linear correlation between x and y

Question 3

Regression calculation

Answer 3

1. assin one to x and y
2. put all values in (stats, 2 var)
3. shift EXE
4. regular results
5. choose depending on relationship
6. r= regrssion

Question 4

P(AUB)

Answer 4

P(A) + P(B) - P(AnB)

Question 5

P(AnB)

Answer 5

P(B) times P(AIB)

Question 6

P(AIB)

Answer 6

P(AnB) / P(B)

Question 7

P(B’UB)

Answer 7

1

Question 8

difference between P(AUB) and P(AnB)

Question 9

random variable

Answer 9

represented by capita X Y Z takes on values that are outcomes of an experiment

e.g. let X be the number of heads you get when tossing two fair coins
X= 0,1,2

Question 10

Continuous random variable that follows a normal distribution

Answer 10

X~N(μ,σ^2)

μ- poluation mean
σ^2 population variance
σ population standard deviation

Question 11

normal distribution properties

Answer 11

• has a bell-shaped curve
• symetrical about the mean
  mean = mode= median
• the area under the bell-shaped curve represents probability
• total area = 1

Question 12

key percentages for a normal distribjution

Answer 12

1 σ 68%
2 σ 95%
3 σ 99.7%

68% of the data is within one standard deviation of the mean

Question 13

if P(X>a) = 0.4

Answer 13

do the normal distribution of P(X<a) = 0.6

Question 14

normal distribtion condition

Answer 14

mean = median = mode

Question 15

μ

Answer 15

centre of bell shaped curve

Question 16

when to use a one tailed test

Answer 16

if you want to trst if population PMCC is greater or smaller than zero

Question 17

when to use a two tailed test

Answer 17

when checking if population is not/ equal to zero

Question 18

PMCC

Answer 18

regular results, r

Question 19

critical value

Answer 19

question states the type of correlattion

Question 20

approximating the binomial distribution

Answer 20

if n is large
if p is close to 0.5
the bionomial distribution X~N(n,p) can be aproximated by the normal distribution

Question 21

aproximating the binomial distribution formulae

Answer 21

λ=np

σ= square root of (np(1-p))

Question 22

when finding probabilities for normal distribution e.g.
P(X<33)

Answer 22

normal cd function

Question 24

for normal distribution to be used the variable has to be

Answer 24

continuous

Question 25

with discrete/ continuous variable all the propbs had add up to

Answer 25

1

Question 27

the curve has points of inflection

Answer 27

one standard deviation from deviation from the mean i.e.

lamda - sigma

(where curve changes concavity)

Question 28

normal distribution is symetical

Answer 28

mean= mode = median