The St. Lawrence Investment Company finds that if the standard deviation for the weekly downtimes of their computer is 2 h or less, then the computer is predictable and planning is facilitated. Twelve weekly downtimes for the computer were randomly selected, and the sample standard deviation was computed to be 2.85 h. The manager of computer operations claims that computer access times are unpredictable because the standard deviation exceeds 2 h. Test her claim, using a 0.025 significance level. Does the variation appear to be too high?
Use the traditional method to test the given hypotheses. Follow the steps outlined in and draw the appropriate graph. In all cases, assume that the population is normally distributed and that the sample has been randomly selected.