16-1

I will teach on how to find the probability of one event or either of two events.

P(event A) = # of favorable outcomes/total # of possible outcomes

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

P(A or B) = P(A) + P(B)( if it is mutually exclusive)

Ex 1: A standard deck of cards with 13 cards each of four suits which are diamonds, spades, clubs, and hearts. Clubs and spades are black, and diamonds and hearts are red. Assuming the deck is shuffled properly what would be the probability that the top card is:

a) a red card

=26/52 = 1/2

b) a black face card

=6/52 = 3/26

c) a 4, 5, or 6 card (any suit)

=12/52= 3/13

Example 2: An integer between 9 and 15, inclusive, is picked randomly. What would be the probability that the integer is:

a) divisible by -3

= 0/7=0

b) odd

= 4/7

c) even

= 3/7

-Sameer