Exam 2

Which of the following is not a binomial experiment? A. Randomly selecting 50 items from a production line and observing if they are good or defective. B. Rolling a die 25 times and observing for an even or odd number. C. Rolling a die 20 times and observing for a number that is less than or equal to 4 or greater than 4. D. Selecting 50 adults and observing if they are in favor of an issue, against it, or have no opinion.

D

If n / N is less than .05, the standard deviation (sigma xbar) of the sampling distribution of the sample mean (xbar) is equal to the population standard deviation

divided by the square root of the sample size.

The values assigned to a population parameter based on the value(s) of a sample statistic are

estimate

For most distributions, we can use the normal distribution to make a confidence interval for a population mean provided that the population standard deviation s is known and the sample size is

greater than or equal to 30.

When making a confidence interval for the population mean using the t procedures, the degrees of freedom for the t distribution are

n - 1.

An error that occurs because of human mistakes is called a

nonsampling error.

In the case of proportion, the sample size is large if

np and nq are both greater than 5.

We can use the normal distribution to approximate the binomial distribution when

np and nq are both more than 5.

The single value of a sample statistic that we assign to the population parameter is a

point estimate.

The sampling distribution is the probability distribution of a

sample

The margin of error for the population mean, assuming is known, is

z multiplied by the standard deviation of the sample mean

The confidence level of an interval estimate is denoted by

(1-a)100%

Forty-four percent of customers who visit a department store make a purchase. What is the probability that in a random sample of 9 customers who will visit this department store, exactly 6 will make a purchase?

.1070

The binomial probability distribution is left-skewed if A. p is greater than .50. B. p is less than .50. C. p is .25 or greater. D. p is equal to .50.

A

The binomial probability distribution is symmetric if A. p is equal to .25. B. p is equal to .50. C. p is less than .50. D. p is greater than .50.

B

Which of the following is NOT a condition of the binomial experiment? A. p is the probability of success, q is the probability of failure, and p + q = 1. B. There are only two trials. C. Each trial has two and only two outcomes. D. The trials are independent.

B

Which of the following is true for the probability of a discrete random variable x? A. P(x)>0 B. 0 < P(x) < 1 C. P(X)<0 D. P(X)=2

B

The mean of a discrete random variable is its

EXPECTED VALUE

For a normal distribution, the z value for the mean is always A. equal to zero. B. negative. C. equal to 1. D. positive.

a

For the standard normal distribution, the mean is A. zero and the standard deviation is 1. B. 1 and the standard deviation is 1. C. 1 and the standard deviation is zero. D. .5 and the standard deviation is .5.

a

How many ways can 7 elements be selected from 14 distinct elements? A. 3432 B. 98 C. 17,297,280 D. 7

a

The probability that a continuous random variable x assumes a single value is always A. equal to zero. B. between zero and 1. C. less than 1. D. greater than zero.

a

The tails of a normal distribution curve A. never meet or cross the horizontal axis. B. are nonsymmetrical. C. meet the horizontal axis at z = 3.0. D. cross the horizontal axis at z = 4.0.

a

The mean of the sampling distribution of the sample mean is

always equal to the population mean.

For the standard normal distribution, the z value gives the distance between the mean and a point on the x-axis in terms of the A. mean. B. standard deviation. C. variance. D. center of the curve.

b

For a normal distribution, the spread of the curve decreases and its height increases as A. the sample size decreases. B. the mean increases. C. the standard deviation decreases. D. the ratio of the mean and standard deviation increases.

c

For the standard normal distribution, what is the area between z = 0 and z = 0.70? A. .2420 B. .7580 C. .2580 D. .7420

c