1

1. The distribution of a random variable X and the distribution of the sample average of X are the same.

   True

   False

QUESTION 2

1. Constructing a confidence interval involves computing the

   probability of error.

   margin of error.

   standard deviation for the population.

   test statistic.

QUESTION 3

1. When the confidence coefficient is .6, alpha is

QUESTION 4

1. When the confidence coefficient is .75, alpha is

QUESTION 5

1. If the sample size is 53 and the population standard deviation is 12.87 then the standard error is ? (Answer to two decimal places)

QUESTION 6

1. For a sample of 54 discount brokers the average price of a $5,000 trade was $33.77. Past surveys of this kind show a standard deviation of $15 so we assume that is theknown population standard deviation. Construct a 90% confidence interval and enter the lower bound for the interval. (Answer to one decimal place anddo notinclude a $ sign).

QUESTION 7

1. For a sample of 54 discount brokers the average price of a $5,000 trade was $33.77. Past surveys of this kind show a standard deviation of $15 so we assume that is the known population standard deviation. Construct a 90% confidence interval and enter the upper bound for the interval. Hint, your answer should be larger than the one for the previous question since they begin with the same summary data. (Answer to one decimal place anddo notinclude a $ sign).

QUESTION 8

1. If there are 33 observations then how many degrees of freedom are there for the t distribution (for a sample mean)?

QUESTION 9

1. If there are 36 observations then how many degrees of freedom are there for the t distribution (for a sample mean)?

QUESTION 10

1. To construct a confidence interval for the population mean when the standard deviation is known we use a

   z value.

   t value.

   F value.

   alpha value.

QUESTION 11

1. To construct a confidence interval for the population mean when the population standard deviation is unknown, and therefore must be estimated, we use a

   z value.

   t value.

   F value.

   alpha value.

QUESTION 12

1. A 2009 sample of New York hotel room prices had an average of $273. Assume this was from a sample of 48 hotels. Assume also that theknown population standard deviationfor the room rates is $72. Construct a 99% confidence interval and report the lower bound for the interval. (Answer to one decimal place anddo notinclude a $ sign).

QUESTION 13

1. A 2009 sample of New York hotel room prices had an average of $273. Assume this was from a sample of 48 hotels. Assume that theknown population standard deviationis $72. Construct a 99% confidence interval and report the upper bound for the interval. Your number should be larger than for the previous problem. (Answer to one decimal place anddo notinclude a $ sign).

QUESTION 14

1. If there are 26 df and the confidence coefficient or cc=.8 then the appropriate t value to use when constructing a confidence interval is (answer to three decimal places).

QUESTION 15

1. If there are 48 df and the confidence coefficient or cc=.95 then the appropriate t value to use when constructing a confidence interval is (answer to two decimal places).

QUESTION 16

1. Alpha is known as the power of a test.

   True

   False

QUESTION 17

1. Given the same data set, a wider confidence interval will have a larger margin of error.

   True

   False

QUESTION 18

1. To construct a confidence interval for the mean you will need

   a point estimate.

   the expected value from the underlying distribution.

   the degrees of freedom.

   a p-value.

QUESTION 19

1. When constructing a confidence interval for the mean, the choice of whether to use a t value or a z value depends on

   the sample size.

   whether or not sigma is known.

   whether or not you are given the degrees of freedom.

   the distribution of the variable for which you are estimating the mean.

QUESTION 20

1. If there are 45 observations in a sample, how many degrees of freedom are there? (The context here is for finding a t value when constructing a confidence interval or testing a hypothesis for the pupoulation mean).

QUESTION 21

1. To find the necessary sample size you need to know the acceptable margin of error.

   True

   False