Exam 7: Sampling and Sampling Distributions

The standard deviation of the sampling distribution of the sample mean is $\sigma$ .

If a population distribution is known to be normal,then it follows that:

A random sample of size 36 is taken from a population with mean 50 and standard deviation 5.What is ?

The internal auditing staff of a local manufacturing company performs a sample audit each quarter to estimate the proportion of accounts that are delinquent more than 90 days overdue.The historical records of the company show that over the past 8 years 14 percent of the accounts are delinquent.For this quarter,the auditing staff randomly selected 250 customer accounts.What is the probability that at least 30 accounts will be classified as delinquent?

A random sample of size 36 is taken from a population with mean 50 and standard deviation 5.Find P ( < 51.5).

The sample standard deviation s is an unbiased estimator of the population standard deviation .

The internal auditing staff of a local manufacturing company performs a sample audit each quarter to estimate the proportion of accounts that are delinquent more than 90 days overdue.The historical records of the company show that over the past 8 years 14 percent of the accounts are delinquent.For this quarter,the auditing staff randomly selected 250 customer accounts.What are the mean and the standard deviation of the sampling distribution of ?

The central limit theorem states that as sample size increases,the population distribution more closely approximates a normal distribution.

The sampling distribution of a sample statistic is the probability distribution of the population of all possible values of the sample statistic.

A random sample of size 1,000 is taken from a population where p = .20.Find P ( < .22).

A sample statistic is an unbiased point estimate of a population parameter if the mean of the populations of all possible values of the sample statistic equals the population parameter.

Find

A manufacturing company measures the weight of boxes before shipping them to the customers.If the box weights have a population mean and standard deviation of 90 lbs.and 24 lbs.respectively,then based on a sample size of 36 boxes,the probability that the average weight of the boxes will exceed 94 lbs.is:

According to a hospital administrator,historical records over the past 10 years have shown that 20% of the major surgery patients are dissatisfied with after-surgery care in the hospital.A scientific poll based on 400 hospital patients has just been conducted. Sixty-four (64)patients indicated that they were dissatisfied with the after surgery care.What are the mean and the standard deviation of the sampling distribution of ?

If the sampled population is finite and at least _____ times larger than the sample size,the standard deviation of decreases as the sample size increases.

If we have a sample size of 100 and the estimate of the population proportion is .10,the standard deviation of the sampling distribution of the sample proportion is:

If p = .8 and n = 50,then we can conclude that the sampling distribution of is approximately a normal distribution.

As the sample size ______________ the variation of the sampling distribution of ___________.

Packages of sugar bags for Sweeter Sugar Inc.have an average weight of 16 ounces and a standard deviation of 0.2 ounces.The weights of the sugar bags are normally distributed.What is the probability that 16 randomly selected packages will have a weight in excess of 16.075 ounces?

The diameter of small Nerf balls manufactured at a factory in China is expected to be approximately normally distributed with a mean of 5.2 inches and a standard deviation of .08 inches.Suppose a random sample of 20 balls is selected.Find the interval that contains 95.44% of the sample means.