The quality control manager at a light bulb factory needs to estimate the mean life of a large shipment of light bulbs. The manufacturer's specifications are that the standard deviations is 100 hours. A random sample of 64 light bulbs indicated a sample mean life of 350 hours.

Answer 1

With you limited data, the best estimate is 350 hours.

If you want a probability statement,

P = mean ± Z (SEm)

SEm = SD/√n

Find table in the back of your statistics text labeled something like "areas under normal distribution" to find the proportion/probability
(P) and its Z score.