A manufacturer of automobile batteries claim that at least 80%of the batteries
that it produces will last 36 months. A consumers’ advocate groupwants to evaluate this
longevity claim and selects a random sample of 28 batteries totest. The following data indicate
the length of time (in months) that each of these batteries lasted(i.e., performed properly
before failure): 42.3, 39.6, 25.0, 56.2, 37.2, 47.4, 57.5, 39.3,39.2, 47.0, 47.4, 39.7, 57.3, 51.8,
31.6, 45.1, 40.8, 42.4, 38.9, 42.9, 34.1, 49.0, 41.5, 60.1, 34.6,50.4, 30.7, 44.1. Now, we would
like to test, at a significance level of 0.05, if there is asignificant evidence that less than 80%
of the batteries will last at least 36 months? Conduct and concludethe test.
