AP Statistics Chapter 6 Review

It turns out that 25 students at Fashionable High School took both the AP Statistics exam and the AP Spanish Language exam. The mean score on the Statistics exam for the 25 students was 2.4 with standard deviation of 0.6, and the mean score on the Spanish Language exam was 2.65 with a standard deviation of 0.55. We want to combine the scores into a single score. What are the correct mean and standard deviation of the combined scores?

• 5.05; 1.15

• 5.05; 1.07

• 5.05; 0.66

• 5.05; 0.81

• 5.05; You cannot determine the standard deviation from this information.

Let the random variable X represent the profit made on a randomly selected day by a certain store. Assume that X is approximately Normal with mean $360 and standard deviation $50. The least profitable 10% of days have a profit of at most how many dollars?

• $244

• $296

• $370

• $424

• $476

Which of the following trials is geometric?

• the number of text messages until you get one from your mom

• the number of text messages that your mom sent

• the number of times the phones rings in a day

• The number of texts in a row that your mom sent

The American Red Cross says that about 11% of the U.S. population has Type B blood. A blood drive is being held at your school.What is the probability that exactly 2 of the first 20 blood donors have Type B blood?

• 20 C 2 (.11)¹⁸(.89)²

• 20 C 2 (.11)²(.89)¹⁸

• (.11)¹⁸(.89)²

• (.11)²(.89)18

32 percent of beach goers end up with some form of sunburn on any given day. Find the standard deviation of a survey of 75 beach goers.

• 16.32

• 17.14

• 1.74

• 4.04

If you want to know how many trials you will need before your first success, use the ????? model.

• Geometric

• Binomial

• Normal

• Calculator

If you want a certain number of successes in a set amount of trials, use the ????? model.

• geometric

• binomial

• normal

• calculato

Given the probability model in the table below, what is the expected value of the random variable?
  X        50          20        5
P(X)     0.1         0.3      0.6

• 14

• 4.67

• 5

• 7.5

A recent survey asked 100 randomly selected adult Americans if they thought that women should be allowed to go into combat situations. The picture is of the results, classified by the gender of the subject. The probability of a “Yes” answer, given that the person was Female, is

• 0.16

• 0.32

• 0.34

• 0.42

(See picture) The probability that a randomly selected subject in the study is Male or answered “No” is:

• 0.18

• 0.68

• 0.78

• 0.84

• 1.02