# The solution to Descriptive and Inferential statistics

1. Suppose we collected data from each person in the class on the number of years since their last math class and their anticipated grade for this statistics class. Determine whether descriptive or inferential statistics would be used to answer each of these research questions:

a. What is the average number of years since the last math class was taken?

b. In general, do students who have been away from a math class more than 10 years anticipate a lower grade than students who have been away from a math class less than 10 years?

c. Is there a significant difference between those who report they will receive an A and those who expect a B in terms of the number of years since math was taken?

d. Draw a frequency distribution that graphs the data for years since the last math class was taken

e. What is the overall percentage of students who anticipate a C?

2. a. What are the critical values for z on a one-tailed test if alpha = .01? .001?

b. What would the critical values be at both levels of significance if it was a two-tailed test?

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## SOLUTION This solution is **FREE** courtesy of BrainMass!

(1) (a) Descriptive statistics (b) Inferential statistics (c) Inferential statistics

(d) Descriptive statistics (e) Descriptive statistics

(2) (a) Critical z- score for one-tailed test with a = 0.01 is 2.3263, and with a = 0.001 is 3.0902

(b) Critical z- scores for two-tailed test with a = 0.01 are -2.5758 and +2.5758, and with a = 0.001 are

-3.2905 and +3.2905.

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