Quick Start Company makes 12-volt car batteries. From historicaldata, the company knows that the life of such a battery is anormally distributed random variable with a mean life of 44 monthsand a standard deviation of 1010 months.
(a) What percentage of Quick Start 12-volt batteries will lastbetween 32 months and 53 months?
(b) If Quick Start does not want to make refunds for more than 10%of its batteries under a full-guarantee policy, how long should thecompany guarantee the 12-volt batteries?
months
(c) Seventy-five 12-volt batteries are randomly selected n=75. Whatis the probability that the mean lifetime of the batteries in thissample will be between 42 and 43 months?
(Input answer to four decimal places)
