A firm that produces light bulbs claims that their lightbulb

A firm that produces light bulbs claims that their lightbulbs last 1500 hours, on average. You wonder if the average might differ from the 1500 hours that the firm claims. To explore this possibility you take a random sample of n = 25 light bulbs purchased from this firm and record the lifetime (in hours) of each bulb. You then conduct an appropriate test of hypothesis. Some of the information related to the hypothesis test is presented below.  

Test of H0:

Solution

The smallest critical value = -2.064

and the larger critical value = 2.064