AP Statistics

If you flip three coins, the probability of getting three heads is 0.125. Which of the following statements follows from this?

• If you flip three coins 1000 times, you will get three heads exactly 125 times.

• If you flip 3 coins 10 times and never get three heads, the probability of getting three heads in the next set of 10 flips is slightly greater than 0.125.

• If you have 20 sets of three coin flips, then at least one set of flips will be three heads.

• If you flip 3 coins 5000 times, the percentage of time you get three heads will be very close 12.5%.

• If you get 3 heads two times in a row, the probability of getting 3 heads again on the next toss of 3 coins is nearly zero.

Forrest has determined that if he gets to the bus stop at 7:30 am, there is a 0.15 probability that he misses the bus. If he arrives at the bus stop three consecutive days at 7:30, what is the approximate probability that he catches the bus all three days?

• 0.003

• 0.386

• 0.450

• 0.614

• 0.997

An event A will occur with probability 0.5. An event B will occur with probability 0.6. The probability that both A and B will occur is 0.1. Which of the following is the conditional probability of A, given B?

• 1/2

• 3/10

• 1/5

• 1/6

• Cannot be determined from the information given.

In a large high school 15% of Sophomores, 25% of Juniors, and 55% of Seniors drive to school. According to the registration office 24% of students are Sophomores, 26% are Juniors, and 30% are Seniors. Suppose we select one student from this school at random and record which class they are in as well as whether they drive to school or not. (a) Draw a tree diagram to model this random process.

• A
• B
• C
• D

• A

• B

• C

• D

• E

• A

• B

• C

• D

• E

Is this a probability distribution?

• No, the sum of p(x) does not equal 1.

• Yes, all p(x) are between 0 and 1.

• No, all p(x) are not between 0 and 1.

• Yes, the sum p(x) is 1.

ASSUME THE GIVEN DISTRIBUTION IS NORMAL.

• A

• B

• C

• D

• E

Is this a probability distribution?

• No

• Yes