The AlwaysOn Company replaces all lightbulbs in large office buildings based on the results of a test.

The test involves collecting a sample of lightbulbs and checking whether the mean of the predicted operating hours remaining is less than or equal to 450 hours.

Present company policy calls for a test sample of 100 lightbulbs in all large office buildings at six monthly intervals.

You may regard the method that predicts the operating hours remaining for an individual lightbulb as giving a precise estimate for the purpose of this analysis.

Suppose that a building currently being tested has lightbulbs with a mean number of hours remaining of