Module 2 and 3 conceptual notes

To compute the probability that in a random sample of n elements, selected without replacement, we will obtain x successes, we would use the:

To compute the probability that in a random sample of n elements, selected without replacement, we will obtain x successes, we would use the hypergeometric probability distribution. See Section 5.7, Hypergeometric Probability Distribution.

If we change a 95% confidence interval estimate to a 99% confidence interval estimate, we can expect the _____.

Width of the Confidence Interval to increase

If arrivals follow a Poisson probability distribution, the time between successive arrivals must follow a(n):

exponential probability distribution.

The numerical value of the standard deviation can never be:

negative

A frequency distribution is a tabular summary of data showing the:

number of items in several classes.

The use of the normal probability distribution as an approximation of the sampling distribution of p̄ is based on the condition that both np and n(1 - p) equal or exceed _____.

5

Cluster sampling is _____.

A Probability Sampling Method

The time it takes to ring up a customer at the grocery store follows an exponential distribution with a mean of 3.5 minutes. What is the variance of this distribution?

A property of the exponential distribution is that the mean of the distribution and the standard deviation of the distribution are equal, so the standard deviation is 3.5. The variance is the square of the standard deviation, so the variance = 3.52 = 12.25. See Section 6.3, Exponential Probability Distribution.

The random variable x is known to be uniformly distributed between 2 and 12. Compute P(x = 6).

A single point is an interval of zero width. This implies that the probability of a continuous random variable assuming any particular value exactly is zero. See Section 6.1, Uniform Probability Distribution.

A 95% confidence interval for a population mean is determined to be 100 to 120. If the confidence coefficient is reduced to .90, the interval for μ _____.

Becomes narrower

A bank manager wishes to estimate the average waiting time for customers in line for tellers. A random sample of 50 times is measured and the average waiting time is 5.7 minutes. The population standard deviation of waiting time is 2 minutes. Which Excel function would be used to construct a confidence interval estimate?

CONFIDENCE.NORM

An auto manufacturer wants to estimate the annual income of owners of a particular model of automobile. A random sample of 200 current owners is selected. The population standard deviation is known. Which Excel function would NOT be appropriate to use to construct a confidence interval estimate?

COUNTIF

The confidence associated with an interval estimate is called the _____.

Confidence Level

The t distribution is a family of similar probability distributions, with each individual distribution depending on a parameter known as the _____.

Degrees of Freedom

When testing water for chemical impurities, results are often reported as BDL, that is, below detection limit. The following data set gives the measurements of the amount of lead in a series of water samples taken from inner-city households (ppm): 5, 7, 12, BDL, 10, 8, BDL, 20, 6 Which of the following is correct?

First, order the values from least to greatest: BDL, BDL, 5, 6, 7, 8, 10, 12, and 20. The middle value, 7, is the median. See Section 3.1, Measures of Location.

Excel's RAND function _____.

Generates random numbers

A newspaper wants to estimate the proportion of Americans who will vote for Candidate A. A random sample of 1000 voters is selected. Of the 1000 respondents, 526 say that they will vote for Candidate A. Which Excel function would be used to construct a confidence interval estimate?

NORM.S.INV

The general form of an interval estimate of a population mean or population proportion is the _____ plus or minus the _____.

Point Estimate, Margin of Error

A manufacturer wants to estimate the proportion of defective items that are produced by a certain machine. A random sample of 50 items is selected. Which Excel function would NOT be appropriate to construct a confidence interval estimate?

STDEV

The value of the ___________ is used to estimate the value of the population parameter.

Sample Statistic

The difference between the value of the sample statistic and the value of the corresponding population parameter is called the _____.

Sampling error

The standard deviation of p̄ is referred to as the _____.

Standard Error of the Population

In a standard normal distribution, what z-score corresponds to the 75th percentile?

The 75th percentile of a standard normal distribution corresponds with z = .67 using a standard normal table. See Section 6.2, Normal Probability Distribution.

Which of the following is not true of discrete probability distributions?

The graph of the distribution always exhibits symmetry.

A display used to compare the frequency, relative frequency, or percent frequency of two categorical variables is a:

stacked bar chart.

The key difference between the binomial and hypergeometric distribution is that with the hypergeometric distribution:

the probability of success changes from trial to trial.