Probability Concepts

Question 1

If a probability is equal to one, the event is _____ to happen

Answer 1

certain

Question 2

what are the two ways we can estimate probabilities

Answer 2

experimental results or model estimates

Question 3

what is the ‘formula’ for working out an experimental estimate of probability

Answer 3

number of favourable outcomes/total number of trials

Question 4

individual outcomes are unpredictable due to?

Answer 4

randomness

Question 5

if we run a very large number of trials, we expect our experimental probabilities to be close to the?

Answer 5

true probabilities

Question 6

what is a common example of a model probability from year 12

Answer 6

the normal distribution

Question 7

what assumption is an example of a model probability when rolling a die

Answer 7

assuming each outcome is equally likely

Question 8

define the sample space

Answer 8

set of all possible outcomes eg: 0,1,2,3,4,5,6,7,8,9,10,11,12

Question 9

random variables can be either ___ or ____

Answer 9

discrete or continuous

Question 10

what is a discrete variable

Answer 10

one where you count and take only whole number values

Question 11

what is a continuous variable

Answer 11

measurement and can be a number in any certain range theoretically

Question 12

the intersection of two venn diagram circles shows the probability of?

Answer 12

A and B

Question 13

the whole space of the two circles of the venn diagram and the overlapping bit shows the probability of?

Answer 13

A or B

Question 14

The space outside the circles but inside the rectangle on a venn diagram represents the probability of?

Answer 14

Neither A nor B

Question 15

what is a conditional probability

Answer 15

the probability of an event happening given that we already know some other event has occured

Question 16

The P(A I B) is the probability of A given B. Which event, A or B, is the one we know has occured?

Answer 16

B

Question 17

What is the formula for conditional probabilities

Answer 17

P(A I B) = P(A n B)/P(B)

Question 18

how is absolute risk calculated

Answer 18

in the same way as probabilities

Question 19

how is relative risk calculated

Answer 19

the risk of one event divided by the risk of the second event

Question 20

relative risk is a r____

Answer 20

ratio

Question 21

a relative risk of 1 means

Answer 21

there is no increased chance of an event due to the risk factor eg: no effect of exercise on the chance of a heart attack

Question 22

a relative risk of less than one means

Answer 22

a decreased risk of the event

Question 23

a relative risk of more than one means

Answer 23

an increased risk of the event

Question 24

what are complementary events

Answer 24

the complement of A is the event A does not happen

Question 25

when are two events mutually exclusive

Answer 25

if A and B never occur at the same time

Question 26

If A and B are mutually exclusive, what would a venn diagram look like

Answer 26

the two circles would not overlap

Question 27

What formula apply to two mutually exclusive events

Answer 27

P(A n B) = 0, P(A U B) = P(A) + P(B) (because there is no overlap to be subtracted)

Question 28

what makes two events independent

Answer 28

if A happening (or not) does not affect the probability of B happening and vice versa

Question 29

If A and B are independent, what formula applies (aka statistical definition of independence)

Answer 29

P(A n B)= P(A) x P(B)