Each of fifteen 60-watt lightbulbs has been randomly placed into an outlet for which the voltage is 3 volts below the line voltage, 2 volts below the line voltage, or equal to the line voltage. The following data are the lifetimes of the bulbs, expressed in days of continuous use.
|
Three volts below line
|
58
|
63
|
46
|
57
|
51
|
|
Two volts below line
|
46
|
59
|
51
|
46
|
42
|
|
Equal to line voltage
|
52
|
48
|
38
|
48
|
42
|
a. What are the null and alternative hypotheses for this test?
b. Use ANOVA and the 0.01 level of significance in testing the null hypothesis identified in part (a).
c. For each sample, construct the 95% confidence interval for the population mean.