AP Statistics Unit 4

This data is normally distributed.  What percent of the data is in the shaded region?

• 68%

• 95%

• 99.7%

• 50%

Jen’s commute to work requires that she take the Blue subway line, then transfer to the Red line. The length of the trip on the Blue line has a mean of 18 minutes with a standard deviation of 2 minutes. The Red line trip takes 12 minutes with a standard deviation of 1 minute. The waiting time between when she gets off the Blue line and her Red line train arrives has mean of 10 minutes and a standard deviation of 5 minutes. Assume (perhaps unrealistically) that these times are independent random variables. What are the mean and standard deviation of her entire commute?

• Mean = 40 minutes; Standard deviation = 8 minutes

• Mean = 40 minutes; Standard deviation = 5.48 minutes

• Mean = 40 minutes; Standard deviation = 2.83 minutes

• Mean = 30 minutes; Standard deviation = 5.48 minutes

What is the probability that a randomly selected girl speaks French?

• 2.14

• .24

• .4

• .8571

In your top dresser drawer are 6 blue socks and 10 grey socks, unpaired and mixed up. One dark morning you pull two socks from the drawer (without replacement, of course!). What is the probability that the two socks match?Hint: try a tree diagram, but be careful with probabilities on the second column of branches.

• 0.075

• 0.375

• 0.450

• 0.500

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.

• A

• B

• C

• D

• E

Is this a probability distribution?

• No

• Yes

If P(A) = 0.24 and P(B) = 0.52 and A and B are independent, what is P(A or B)? Hint: Use formula card

• 0.1248

• 0.28

• 0.6352

• The answer cannot be determined

If 10 is added to every value in a set of data, what will happen to the value of the mean?

• it will increase by 10

• it will decrease by 10

• it will stay the same

• it will both increase and decrease

If 10 is added to every value in a set of data, what will happen to the value of the standard deviation?

• it will increase

• it will decrease

• it will stay the same

• it will both increase and decrease