1. A manufacturer claims that their light bulbs have an average life span of µ = 1200 hours with a standard deviation of σ = 25. If you randomly test 36 light bulbs and find that their average lifespan is X‾ = 1150, does a .95 confidence interval for µ suggest that the claim µ = 1200 is unreasonable?
2. Compute a .95 confidence interval for the mean in the following situations: (a) n = 12, σ = 22, X‾= 65, (b) n = 22, σ = 10, X‾= 185, (c) n = 50, σ = 30, X‾ = 19.