AP Stat Sampling Distribution

According to data from the United States Elections Project, only 36 percent of eligible voters voted in the 2014 elections. For random samples of size 40, which of the following best describes the sampling distribution of pˆ, the sample proportion of people who voted in the 2014 elections?

• The sampling distribution is skewed to the left, with mean 0.36 and standard deviation 0.076.

• The sampling distribution is skewed to the right, with mean 0.64 and standard deviation 0.006.

• The sampling distribution is approximately normal, with mean 0.36 and standard deviation 0.076.

• The sampling distribution is approximately normal, with mean 0.36 and standard deviation 0.006.

• The sampling distribution is approximately normal, with mean 0.64 and standard deviation 0.076.

At a certain restaurant, the distribution of wait times between ordering a meal and receiving the meal has mean 11.4 minutes and standard deviation 2.6 minutes. The restaurant manager wants to find the probability that the mean wait time will be greater than 12.0 minutes for a random sample of 84 customers. Assuming the wait times among customers are independent, which of the following describes the sampling distribution of the sample mean wait time for random samples of size 84 ?

• (A) Approximately normal with mean 11.4 minutes and standard deviation 2.6 minutes

• (C) Approximately normal with mean 12.0 minutes and standard deviation 2.6 minutes

• (D) Binomial with mean 84(0.41) minutes and standard deviation 84(0.41)(0.59) minutes

• (E) Binomial with mean 84(0.5) minutes and standard deviation 84(0.5)(0.5) minutes

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If I tell you that you scored at the 55th percentile on your last exam, you would know:

• 55% of the class scored as good or worse than I did.

• I earned a 55% on the exam.

• I failed the exam.

• 45% of the class scored worse than I did.