a firm producing light bulbs wants to know if it can clam that its light bulbs last 1000 hours to answer this question the firm takes a random sample...

a firm producing light bulbs wants to know if it can clam that its light bulbs last 1000 hours to answer this question the firm takes a random sample of 100 bulbs and finds the average life time for this sample is 970 hour and the standard deviation is 80 hours . can the firm clam that the average life time is 1000 hours at the 5% level of significance ?