Statistics: Probability Rules

In an AP Statistics class, 57% of students eat breakfast in the morning, 80% of them floss their teeth, and 46% of the students do both.  What is the probability that a randomly chosen student eats breakfast or flosses their teeth?

• 91%

• 9%

• 11%

• 34%

In an AP Statistics class, 57% of students eat breakfast in the morning, 80% of them floss their teeth, and 46% of the students do both.  What is the probability that a randomly chosen student eats breakfast but does not floss their teeth?

• 9%

• 11%

• 34%

• 91%

Five juniors and four seniors have applied for two open student council positions, and administrators have decided to pick two new members randomly.  What is the probability that they are both from the same grade?

• .395

• .444

• .506

• .569

A fair coin has come up "heads" 10 times in a row.  The probability that the coin will come up heads on the next flip is:

• greater than 50%, it's due to happen.

• 50%

• less than 50%, since tails is happening so much.

• Can't be determined

Pepsi is running a sales promotion in which 12% of all bottles have a "FREE" logo under the cap.  If you buy a 6-pack of bottles, what is the probability that you will find at least 1 "FREE" logo?

• .464

• .536

• .12

• 0

An ice cream stand owner reports that 12% of the cones they sell are "JUMBO" size.  You want to see what a "JUMBO" cone looks like so you stand and watch the sales for a while.  What is the probability that the first "JUMBO" cone is the fourth cone you see them sell?

• 8%

• 33%

• 40%

• 60%

A bicycle shop equips 60% of its bikes with a water bottle holder, and 55% of its bikes are equipped with a kick stand.  34% of the bikes have both features.  What is the probability that a randomly chosen bike has a kick stand GIVEN THAT it has a water bottle holder?

• 34%

• 56.7%

• 61.8%

• 81%

The probability of a tourist visiting an area cave is .7, and of a tourist visiting a nearby park is .6.  The probability of visiting both places on the same day is .4.  The probability that a tourist visits at least one of these two places is:

• .08

• .28

• .42

• .9

100 people were surveyed.  54 were female, and 46 were male.  33 of the females said they were democrats, and 30 of the males said they were republicans.  If a person is randomly selected, what is the probability that its a democrat  GIVEN THAT it is a female?

• .67

• .49

• .61

• .33

100 people were surveyed.  54 were female, and 46 were male.  33 of the females said they were democrats, and 30 of the males said they were republicans.  If two people are randomly selected, what is the probability they are both males?

• .30

• .46

• .25

• .21