Probability of an Event

If the probability of a student passing exam A is 0.4, exam B is 0.6, and the probability of passing both exams is 0.3, what is the probability of passing at least one exam?

• 0.25

• 0.5

• 0.6

• 0.7

• 0.8

Of 52 cards, if A is the event of getting a heart card and B is the event of getting a king card, what is P(A U B) if A and B are not mutually exclusive?

• 6/13

• 4/13

• 2/5

• 1/2

• 1/52

• .2855
• .6246
• .0922
• .3230

If events A and B are independent, and the probability that event A occurs is 83%, what must be true?

• The probability that event B occurs is 17%.

• The probability that event B occurs is 83%.

• The probability that event A occurs, given that event B occurs, is 83%.

• The probability that event B occurs, given that event A occurs, is 83%.

A survey of the 12th grade students at Tucker High School found that 84% of the seniors have their driver’s licenses, 16% of seniors take the bus every day to school, and 14% of the seniors have driver’s licenses and take the bus to school every day.

To the nearest whole percent, what is the probability that a senior takes the bus to school every day, given that they have a driver’s license?

• 17%

• 19%

• 36%

• 70%

A bag contains one red pen, four black pens, and three blue pens. Two pens are randomly chosen from the bag and are not replaced.

To the nearest hundredth, what is the probability that a black pen is chosen first and then another black pen is chosen?

• 0.02

• 0.19

• 0.21

• 0.25

Which two events are independent?

• A and X

• A and Y

• B and X

• B and Y

• 0.2

• 0.3

• 0.4

• 0.5

What is the probability that a student does play a sport given they do not play an instrument? 

• .2

• .2222

• .10

• .5

Of the students at Lakeland High School, 5/16 are juniors, 2/3 buy lunch at school, and 1/4 are juniors that buy their lunch at school. If a student is chosen at random, what is the probability that they buy their lunch at school, given they are a junior? Hint: Drawing a Venn Diagram may help. Write as a fraction in simplest form.