Exam 7: Sampling and Sampling Distributions

Catherine Chao, Director of Marketing Research, needs a sample of Ottawa households to participate in the testing of a new toothpaste package.If 40% of the households in Ottawa prefer the new package, the probability that Catherine's random sample of 300 households will have a sample proportion greater than 45% is ___.

Increasing the sample size causes the sampling distribution of to ___.

Suppose a population has a mean of 870 and a variance of 1,600.If a random sample is size 64 is drawn from the population, the probability that the sample mean is between 860 and 875 is ___.

Suppose 40% of the population possess a given characteristic.If a random sample of size 300 is drawn from the population, then the probability that 44% or fewer of the samples possess the characteristic is ___.

A random sample of size 100 is drawn from a population with a standard deviation of 10.If only 5% of the time a sample mean greater than 20 is obtained, the mean of the population is ______

Financial analyst Larry Potts needs a sample of 100 securities listed on either the Toronto Stock Exchange (TSX)or the New York Stock Exchange (NYSE).According to the Report on Business Magazine's "Stock Market Data Bank," 2,531 TSX securities and 746 NYSE securities were traded on the previous business day.Larry directs his staff to randomly select 77 TSX and 23 NYSE securities.His sample is a ___.

Suppose a population has a mean of 870 and a variance of 8,100.If a random sample is size 36 is drawn from the population, the probability that the sample mean is between 840 and 900 is ___.

Suppose a population has a mean of 450 and a variance of 900.If a random sample is size 100 is drawn from the population, the probability that the sample mean is between 448 and 453 is ___.

Financial analyst Larry Potts needs a sample of 100 securities listed on the Toronto Stock Exchange.The current issue of the Report on Business Magazine, has an alphabetical list of the 2,531 securities that are listed in the "Toronto Exchange Composite Transactions," an alphabetical listing of all securities traded on the previous business day.Larry uses a table of random numbers to select 100 numbers between 1 and 2,531.His sample is a ___.

Systematic sampling is a type of nonrandom sampling technique.

The two major categories of sampling methods are proportionate and disproportionate sampling.

If random variable X is distributed according to a uniform distribution between 0 and 1 (X ~ U[0, 1]), and 100 random samples of sizes 35-40 were taken, the standard deviation of the sample means would be ______.

In a random sampling technique every unit of the population has a randomly varying chance or probability of being included in the sample.

Alice Zhong is the VP of Operations at Pearl Financial Services.She wants to measure customer satisfaction after a new website and other changes were introduced a few months ago.For this purpose, she instructs her staff to prepare a questionnaire and send it to the first 200 clients in their alphabetical list of active clients.This is an example of ______.

Financial analyst Larry Potts needs a sample of 100 securities listed on the Toronto Stock Exchange.The current issue of the Report on Business Magazine, has an alphabetical list of the 2,531 securities that are listed in the "Toronto Exchange Composite Transactions," an alphabetical listing of all securities traded on the previous business day.Larry randomly selects the 7th security as a starting point, and selects every 25th security thereafter (7, 32, 57, etc.).His sample is a ___.

The central limit theorem states that if the sample size, n, is large enough (n ≥30), the distribution of the sample means is uniformly distributed regardless of the shape of the population.

Suppose the population of all public Universities shows the annual parking fee per student is normally distributed with a mean of $110 with a standard deviation of $18.If a random sample of size 49 is drawn from the population, the probability of drawing a sample with a mean of less than $92 is _______.

Saving time and money are reasons to take a sample rather than do a census.

Albert Abbasi, VP of Operations at Ingleside International Bank, is evaluating the service level provided to walk-in customers.Accordingly, he plans a sample of waiting times for walk-in customers.If the population of waiting times has a mean of 15 minutes and a standard deviation of 4 minutes, the probability that Albert's sample of 64 will have a mean less than 14 minutes is ___.

Suppose 30% of a population possess a given characteristic.If a random sample of size 1200 is drawn from the population, then the probability that less than 348 possess that characteristic is ___.