Exam 8: Sampling Distributions

If a population is skewed, based on the Central Limit Theorem, what is a good rule of thumb for assuming the sampling distribution of is approximately normal?

A department store claims that its average customer satisfaction rating is 28.5.We believe that this rating is too high, so we randomly sample 40 customers and find a sample average of 25.2.If the standard deviation of customer satisfaction for this store is 13.1, what is the probability of observing a sample at least this far below the claimed mean, assuming the claim is true?

If the monthly rents of all one-bedroom apartments in a small town are known to be normally distributed with a mean of $175 and a standard deviation of $35, which of the following would be the least likely individual rent that you might expect to find?

Suppose we know that the proportion of objects in a population that have a particular characteristic of interest is 0.10.Are there any concerns if we want to calculate probabilities for the sampling distribution of n = 40 using a normal approximation?

A _________ is any quantity computed from values in a sample.

Homeowners who recently bought their houses from a local developer allege that 30% of the houses this developer constructs have some major defect that will require substantial repairs.To test this allegation, we randomly sample 20 houses constructed by the developer and find that two of the homes do, indeed, have some major defect.If the allegation is correct, what is the probability of observing at most two defective homes out of a random sample of 20?

All statistics may be treated as:

If the sample size is large (n ≥ 30), then, regardless of the population distribution, which of the following summarizes the sampling distribution of random variable ?

Concerning the sampling distribution of , what is the significance of the conditions np ≥ 5 and n(1 - p) ≥ 5?

It is believed that 15% of people who fly on commercial airliners are "very concerned" about the safety of the carrier they have chosen.If this statement is accurate, what is the probability that out of 150 randomly selected people who fly on commercial airliners, between 20 and 25 of them are "very concerned" about the safety of the carrier that they have chosen?

What effect does increasing the sample size have on the sampling distribution of ?

According to the Central Limit Theorem, as the sample size (n) from a non-normal population increases:

To better understand the student body, a college administrator takes a census of all students currently enrolled at the college.From the census, he finds that the range of ages at this school is 41 years.In this example, 41 years is a:

Heights of children entering kindergarten are normally distributed with a mean of 103 cm and a standard deviation of 1.27 cm.What is the probability that a random sample of 8 children will have an average height more than 103.5 cm?

A simple random sample (SRS) of size n is best defined as:

The speed at which an automated assembly line produces a product follows a normal distribution, with a mean production time of 32.20 sec and a standard deviation of 1.05 sec.A full production run from this line consists of 20 completed products.What is the probability that a full production run will take less than 32 sec, on average, to finish?

If the population is perfectly normal, the sampling distribution of will be:

Which of the following statements is true about the sampling distribution of the sample proportion ?

In a major city in the northwest United States, 28% of the days experience some period of rain.What is the probability that more than 12 days out of a random sample of 31 days will experience some period of rain?

Because