Conditional Probability CHAPTER 4.3

INTRO TO VENN DIAGRAMS - PETS

UNION, INTERSECTION, COMPLIMENT

The probability that the second event B occurs given that the first event A has occurred can be found by dividing the probability that both events occurred by the probability that the first event has occurred.

P(B|A) =

CONDITIONAL PROBABILITY

)(

)(

AP

BAP

A box contains black chips and white chips. A person selects two chips without replacement. The probability of selecting a black chip and a white chip is 15/56, and the probability of selecting a black chip on the first draw is 3/8.

How many chips are there?Create a Venn Diagram to represent the

probabilitiesFind the probability of selecting two white chipsFind the probability of selecting the white chip on

the second draw, given that the first chip selected was a black chip.

SELECTING COLORED CHIPS

At a large university, the probability that a student takes calculus and is on the dean’s list is 0.042. The probability that a student is on the dean’s list is 0.21. Find the probability that the student is taking calculus, given that he or she is on the dean’s list.

COLLEGE COURSES

The probability that Sam parks in a no-park zone and gets a parking ticket is 0.06, and the probability that Sam cannot find a legal parking space and has to park in the no-parking zone is 0.20. On Tuesday, Sam arrives at school and has to park in the no-parking zone. Find the probability that he will get a parking ticket.

PARKING TICKETS

A recent survey asked 100 people if they thought women in the armed forces should be permitted to participate in combat. The results of the survey are shown. Find the following probabilities:

The respondent answered yes, given that the respondent was a female

The respondent was a male, given that the respondent answered no

SURVEY ON WOMEN IN THE MILITARY

Gender Yes No Total

Male 32 18 50

Female 8 42 50

Total 40 60 100

A game is played by drawing 4 cards from an ordinary deck and replacing each card after it is drawn. Find the probability that at least 1 ace is drawn.

AT LEAST PROBABILITIES: DRAWING CARDS

A coin is tossed 5 times Find the probability of getting at least 1 tail.

TOSSING COINS

The Neckware Association of America reported that 3% of ties sold in the U.S. are bow ties. If 4 customers who purchased a tie are randomly selected, find the probability that at least 1 selected a bow tie.

FORMAL ATTIRE

Pg. 228 #1-8

APPLYING THE CONCEPTS