A supplier manufactures rubber baby buggy bumpers for the bu

A supplier manufactures rubber baby buggy bumpers for the bumper cars. A random sample of 100 bumpers is taken and the sample mean life is 3.5 years with a standard deviation of .75 years. a. The law requires 98% confidence of operation when scheduling bumper replacement. What are the lower-limit of the two-sided confidence interval? b. The supplier claims that the mean life is at least 4 years. Is there evidence to support the claim at = .04?

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