A supplier manufactures rubber baby buggy bumpers for the bumper cars. A random sample of 49 bumpers is taken and the sample mean life is 3.5 years with a standard deviation of .5 years. The law requires 95% confidence of operation when scheduling bumper replacement.

a)What are the lower-limit and the upper-limit of the two-sided confidence interval?

b)The supplier claims that their bumper last at least 4 years. Check their claim at alpha = .06