Probability

Question 1

what the definition of probability

Answer 1

scaled-down group behaviour applied to a single individual”

Question 2

Define experiment

Answer 2

any procedure the outcome of which cannot be predicted with certainty

Question 3

define sample space

Answer 3

the set of all possible outcomes

Question 4

what does P(E) mean?

Answer 4

probability of event E

p(E) = 0 implies event E is impossible
P(E) = 1 implies event E is CERTAIN

A larger P(E) implies event E has greater likelihood of occurring

Question 5

what does it mean if two events are mutually exclusive

Answer 5

If they have no elements in common, i.e. if they cannot both happen at the same time

Question 6

If A, B, C are mutually exclusive events:

Answer 6

P(A or B) = P(A) + P(B)
P(A or B or C or …) = P(A) + P(B) + P(C) + …

• For a certain population:
  P(type O blood) = 0.43; P(type A blood) = 0.20
  P(type O or type A blood) = 0.43+0.20 = 0.63

Question 7

If A, B, C … are not mutually exclusive events:

Answer 7

P(A or B) = P(A) + P(B) - P(A and B)

P(A or B or C) = P(A) + P(B) + P(C) - P(A and B) - P(B and C) - P(C and A) + P(A and B and C)

Question 8

conditional probabilities

Answer 8

this is when we restrict our comments to only the male population or the female population

Question 9

how to work out conditional probabilities

Answer 9

if working out the probability of A given B then you do the probability of A and B divided by the probability of B