AP Stats Chapter 9 Review

I collect a random sample of size n from a population and from the data collected compute a 95% confidence interval for the mean of the population.  Which of the following would produce a wider confidence interval, based on these same data?

• Use a larger confidence level

• Use a smaller confidence level

• Use the same confidence level, but compute the interval n times.  Approximately 5% of these intervals will be larger

• Increase the sample size

You are told that the proportion of those who answered "yes" to a poll about internet use is 0.70, and that the standard error is 0.0459.  The sample size is

• 50

• 99

• 100

• 200

The standardized test scores of 16 students have mean x̄ = 200 and standard deviation s = 20.  What is the standard error of x̄?

• 20

• 10

• 5

• 1.25

After a college's football team once again lost a football game to the college's arch rival, the alumni association decided to conduct a survey to see if alumni were in favor of firing the coach.  Let p represent the proportion of all living alumni who favor firing the coach.  Which of the following is the smallest sample size needed to guarantee an estimate that's within 0.05 of p at a 95% confidence level?

• 269

• 385

• 538

• 768

A claimed psychic was presented with 200 cards face down and asked to determine if the card was one of five symbols: a star, cross, circle, square, or three wavy lines.  The "psychic" was correct in 50 cases.  To determine if he has ESP, we test the hypothesis H₀:  p = 0.20, Hₐ: p > 0.20, where p represents the true proportion of cards for which the psychic would correctly identify the symbol in the long run.  Assume the conditions for inference are met.  The P-value is 

• between .10 and .05

• between .05 and .025

• between .025 and .01

• between .01 and .001

An SRS of 100 teachers showed that 64 owned smartphones.  An SRS of 100 students showed that 80 owned smartphones.  Let pₑ be the proportion of all teachers who own smartphones, and let pₓ be the proportion of all students who own smartphones.  A 95% confidence interval for the difference pₑ - pₓ is 

• (0.264, 0.056)

• (0.098, 0.222)

• (-0.222, -0.098)

• (-0.283, -0.038)

If P(A) = 0.24 and P(B) = 0.52 and A and B are independent, what is P(A or B)?

• 0.1248

• 0.28

• 0.6352

• 0.76

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?

• 0.075

• 0.375

• 0.450

• 0.500

A simple random sample of 1000 Americans found that 62% were satisfied with the service provided by the dealer from which they bought their car.  A simple random sample of 1000 Canadians found that 59% were satisfied with the service provided by the dealer from which they bought their car.  The sampling variability associated with these statistics is

• exactly the same

• not exactly the same, but very close

• much smaller for the sample of Canadians because the population of Canad is much smaller than that of the United States, hence the sample is a larger proportion of the population.

• smaller for the sample of Canadians because the percent satisfied was smaller than that of Americans.

• The slope decreased and the r² increased.
• The slope increased and the r² decreased.
• The slope decreased but r² remained the same.
• Both slope and r² remained the same.