Probability of an event – the relative frequency of this. set of outcomes over an infinite number of trials. Pr(A) is the probability of event A. An Introduction to Basic Statistics and Probability – p.

Conditional probability is defined as the likelihood of an event or outcome occurring, based on the occurrence of a previous event or outcome. Conditional probability is calculated by multiplying the probability of the preceding event by the updated probability of the succeeding, or conditional, event.

If events A and B are mutually exclusive, then the probability of A or B is simply: p(A or B) = p(A) + p(B).

The probability that Events A and B both occur is the probability of the intersection of A and B. The probability of the intersection of Events A and B is denoted by P(A ∩ B). If Events A and B are mutually exclusive, P(A ∩ B) = 0.

If A and B are two events in a sample space S, then the conditional probability of A given B is defined as P(A|B)=P(A∩B)P(B), when P(B)>0.

There are 7 ways of choosing the first, 6 ways of choosing the second and 5 ways of choosing the third. 7*6*5=210. So you get 7∗6∗53∗2∗1 7 ∗ 6 ∗ 5 3 ∗ 2 ∗ 1 = 35 ways.

64

Answer: In the U.S.A. there are 293 different ways to make $1.

Answer: 100 pennies, 20 nickels, 10 dimes, or 4 quarters; each = 1 dollar. Answer: 10 nickels + 5 dimes = 1 dollar. Using more than one type of coin, what is the smallest number of coins you can use to make a dollar? Answer: Six coins: 3 quarters + 2 dimes + 1 nickel = 1 dollar.

combinations

The combinations would ignore digit order (thus 12 and 21 are the same.) Then you have 9 choices for the first digit and 8 choices for the second one. Making a total of 9*8= 72 combinations. However since each one has a reversible pair the answer is half that so 36.