Quick Start Company makes 12 -volt car batteries. After many years of product testing, the company knows that the average life of a Quick Start battery is normally distributed, with a mean of 45 months and a standard deviation of 8 months. (a) If Quick Start guarantees a full refund on any battery that fails within the 36 -month period after purchase, what percentage of its batteries will the company expect to replace? (b) If Quick Start does not want to make refunds for more than 10 % of its ba