COMPLETE EACH QUIZ ON SEPARATE WORD DOCUMENT

CHOOSE THE CORRECT MULTIPLE CHOICE ANSWER

QUIZ 3:

QUESTION 1

1.

A numerical description of the outcome of an experiment is called a

		descriptive statistic
		probability function
		variance
		random variable

5 points

QUESTION 2

1.

A random variable that can assume only a finite number of values is referred to as a(n)

		infinite sequence
		finite sequence
		discrete random variable
		discrete probability function

5 points

QUESTION 3

1.

A random variable that may take on any value in an interval or collection of intervals is known as a

		continuous random variable
		discrete random variable
		continuous probability function
		finite probability function

5 points

QUESTION 4

1.

A description of the distribution of the values of a random variable and their associated probabilities is called a

		probability distribution
		random variance
		random variable
		expected value

5 points

QUESTION 5

1.

The expected value for a binomial probability distribution is

		E(x) = Pn(1 – n)
		E(x) = P(1 – P)
		E(x) = nP
		E(x) = nP(1 – P)

5 points

QUESTION 6

1.

The variance for the binomial probability distribution is

		var(x) = P(1 – P)
		var(x) = nP
		var(x) = n(1 – P)
		var(x) = nP(1 – P)

5 points

QUESTION 7

1.

Which of the following is not a characteristic of an experiment where the binomial probability distribution is applicable?

		the experiment has a sequence of n identical trials
		exactly two outcomes are possible on each trial
		the trials are dependent
		the probabilities of the outcomes do not change from one trial to another

5 points

QUESTION 8

1.

The number of electrical outages in a city varies from day to day. Assume that the number of electrical outages (x) in the city has the following probability distribution.
x f(x)
0 0.80
1 0.15
2 0.04
3 0.01

The mean and the standard deviation for the number of electrical outages (respectively) are

		2.6 and 5.77
		0.26 and 0.577
		3 and 0.01
		0 and 0.8

5 points

QUESTION 9

1.

The center of a normal curve is

		always equal to zero
		is the mean of the distribution
		cannot be negative
		is the standard deviation

5 points

QUESTION 10

1.

A normal distribution with a mean of 0 and a standard deviation of 1 is called

		a probability density function
		an ordinary normal curve
		a standard normal distribution
		none of these alternatives is correct

5 points

QUESTION 11

1.

A negative value of Z indicates that

		the number of standard deviations of an observation is to the right of the mean
		the number of standard deviations of an observation is to the left of the mean
		a mistake has been made in computations, since Z cannot be negative
		the data has a negative mean

10 points

QUESTION 12

1.

Which of the following is not a characteristic of the normal probability distribution?

		The mean, median, and the mode are equal
		The mean of the distribution can be negative, zero, or positive
		The distribution is symmetrical
		The standard deviation must be 1

10 points

QUESTION 13

1.

Z is a standard normal random variable. The P (1.41 ≤ Z ≤ 2.85) equals

		0.4978
		0.4207
		0.9185
		0.0771

10 points

QUESTION 14

1.

X is a normally distributed random variable with a mean of 8 and a standard deviation of 4. The probability that X is between 1.48 and 15.56 is

		0.0222
		0.4190
		0.5222
		0.9190

10 points

QUESTION 15

1.

Larger values of the standard deviation result in a normal curve that is

		shifted to the right
		shifted to the left
		narrower and more peaked
		wider and flatter

QUIZ 4:

QUESTION 1

1.

Parameters are

		numerical characteristics of a sample
		numerical characteristics of a population
		the averages taken from a sample
		numerical characteristics of either a sample or a population

10 points

QUESTION 2

1.

Stratified random sampling is a method of selecting a sample in which

		the sample is first divided into strata, and then random samples are taken from each stratum
		various strata are selected from the sample
		the population is first divided into strata, and then random samples are drawn from each stratum
		None of these alternatives is correct.

10 points

QUESTION 3

1.

A theorem that allows us to use the normal probability distribution to approximate the sampling distribution of sample means and sample proportions whenever the sample size is large is known as the

		approximation theorem
		normal probability theorem
		central limit theorem
		central normality theorem

10 points

QUESTION 4

1.

In point estimation

		data from the population is used to estimate the population parameter
		data from the sample is used to estimate the population parameter
		data from the sample is used to estimate the sample statistic
		the mean of the population equals the mean of the sample

10 points

QUESTION 5

1.

The sample statistic s is the point estimator of

		μ
		σ
		x ̅
		p ̅

10 points

QUESTION 6

1.

The sample mean is the point estimator of

		μ
		σ
		x ̅
		p ̅

10 points

QUESTION 7

1.

The standard deviation of all possible x ̅ values is called the

		standard error of proportion
		standard error of the mean
		mean deviation
		central variation

10 points

QUESTION 8

1.

A sample statistic, such as a sample mean, is known as

		a statistic
		a parameter
		the mean deviation
		the central limit theorem

10 points

QUESTION 9

1.

The purpose of statistical inference is to provide information about the

		sample based upon information contained in the population
		population based upon information contained in the sample
		population based upon information contained in the population
		mean of the sample based upon the mean of the population

10 points

QUESTION 10

1.

Random samples of size 81 are taken from an infinite population whose mean and standard deviation are 200 and 18, respectively. The distribution of the population is unknown. The mean and the standard error of the mean are

		200 and 18
		81 and 18
		9 and 2
		200 and 2

QUIZ 5:

QUESTION 1

1.

For the interval estimation of μ when σ is known and the sample is large, the proper distribution to use is

		the normal distribution
		the t distribution with n degrees of freedom
		the t distribution with n + 1 degrees of freedom
		the t distribution with n + 2 degrees of freedom

5 points

QUESTION 2

1.

An estimate of a population parameter that provides an interval of values believed to contain the value of the parameter is known as the

		confidence level
		interval estimate
		parameter value
		population estimate

5 points

QUESTION 3

1.

The value added and subtracted from a point estimate in order to develop an interval estimate of the population parameter is known as the

		confidence level
		margin of error
		parameter estimate
		interval estimate

5 points

QUESTION 4

1.

Whenever the population standard deviation is unknown and the population has a normal or near-normal distribution, which distribution is used in developing an interval estimation?

		standard distribution
		z distribution
		alpha distribution
		t distribution

5 points

QUESTION 5

1.

The z value for a 97.8% confidence interval estimation is

		2.02
		1.96
		2.00
		2.29

5 points

QUESTION 6

1.

The t value for a 95% confidence interval estimation with 24 degrees of freedom is

		1.711
		2.064
		2.492
		2.069

5 points

QUESTION 7

1.

As the sample size increases, the margin of error

		increases
		decreases
		stays the same
		increases or decreases depending on the size of the mean

5 points

QUESTION 8

1.

The ability of an interval estimate to contain the value of the population parameter is described by the

		confidence level
		degrees of freedom
		precise value of the population mean μ
		degrees of freedom minus 1

5 points

QUESTION 9

1.

In general, higher confidence levels provide

		wider confidence intervals
		narrower confidence intervals
		a smaller standard error
		unbiased estimates

5 points

QUESTION 10

1.

An interval estimate is a range of values used to estimate

		the shape of the population's distribution
		the sampling distribution
		a sample statistic
		a population parameter

5 points

QUESTION 11

1.

As the number of degrees of freedom for a t distribution increases, the difference between the t distribution and the standard normal distribution

		becomes larger
		becomes smaller
		stays the same
		becomes negative

10 points

QUESTION 12

1.

In order to determine an interval for the mean of a population with unknown standard deviation a sample of 61 items is selected. The mean of the sample is determined to be 23. The number of degrees of freedom for reading the t value is

		22
		23
		60
		61

10 points

QUESTION 13

1.

After computing a confidence interval, the user believes the results are meaningless because the width of the interval is too large. Which one of the following is the best recommendation?

		Increase the level of confidence for the interval.
		Decrease the sample size.
		Increase the sample size.
		Reduce the population variance.

10 points

QUESTION 14

1.

A sample of 225 elements from a population with a standard deviation of 75 is selected. The sample mean is 180.The 95% confidence interval for μ is

		105.0 to 225.0
		175.0 to 185.0
		100.0 to 200.0
		170.2 to 189.8

10 points

QUESTION 15

1.

The sample size needed to provide a margin of error of 2 or less with a .95 probability when the population standard deviation equals 11 is

		10
		11
		116
		117