Practice Quiz-Lecture 3

Question 1

The shape of a normal distribution is:

Answer 1

Bell-shaped

Question 2

The mean and standard deviation (SD) of a standard normal distribution are

Answer 2

Mean = 0 and SD = 1

Question 3

About _______% of data lie within 1 SD of the mean

Answer 3

68%

Question 4

About ______% of data lie below 1 SD of the mean

Answer 4

16%

Question 5

About ______% of data lie within 2 SD of the mean

Answer 5

95%

Question 6

About _____% of data lie outside 2 SD of the mean

Answer 6

5%

Question 7

The sampling distribution describes the distribution of

Answer 7

sample mean

Question 8

The standard error is a population parameter

Answer 8

False
-The standard error is the standard deviation of the sample mean. It is not a population parameter. The standard error is written as sigma divided by square root of n, where sigma is the population standard deviation and n is the sample size. Thus, the standard error depends upon the sample size n. Hence, the standard error cannot be a population parameter.

Question 9

The margin of error depends upon the sample size

Answer 9

True
-The margin of error is equal to critival value multiplied by standard error. The standard error is written as the standard deviation divided by the square root of n. Hence, the margin of error depends upon the sample size n.

Question 10

The margin of error is equal to critival value multiplied by standard error. The standard error is written as the standard deviation divided by the square root of n. Hence, the margin of error depends upon the sample size n.

Answer 10

True
-The margin of error is written as critical value times the standard error. The critical value is a percentile from a normal distribution when the population standard deviation is known.

Question 11

The area under the standard normal distribution above the critical value Z underscore (1-alpha/2) is

Answer 11

alpha/2 * 100%

Question 12

The area under the standard normal distribution between -Z underscore (1-alpha/2) and Z underscore (1-alpha/2) is

Answer 12

(1 - alpha) * 100%

Question 13

When calculating 90% confidence interval, the area under the standard normal distribution outside minus and plus critical values is

Answer 13

10%

Question 14

Suppose you are calculating confidence interval for population mean. When the population standard deviation is not known and the sample size is small, the critical value is obtained from a:

Answer 14

t distribution with n-1 degrees of freedom

Question 15

When calculating confidence interval for population proportion and the sample size is small, obtain critical value from

Answer 15

standard normal distribution