Illowsky Ch 9 # 77 (discussions)

An article in the San Jose Mercury News stated that students in the California state university system take 4.5 years, on average, to finish their undergraduate degrees. Suppose you believe that the mean time is longer. You conduct a survey of 49 students and obtain a sample mean of 5.1 with a sample standard deviation of 1.2. Do the data support your claim at the 1% level?

A 1%of significance means that . It is a test of a single population mean.

a. H₀: = (the mean time is 4.5 years)

b. H_a: > (since you believe that the mean time is longer than 4.5 years)

c. Random variable: = the average time to .

d. Distribution for the test: There is no population standard deviation given. This means that the distribution for the test is a Students-t distribution

e. What is the test statistic?

f. to calculate p-value we can use p-value calculator

http://www.socscistatistics.com/pvalues/tdistribution.aspx

Interpretation of the p-value:

g. i. Alpha: 0.01

ii. Decision: Reject (OR fail to reject ?) the null hypothesis.

iii. Reason for decision:

iv. Conclusion: At 1% level of significance, the sample data show