The shelf life of a battery produced by one major company is known to be normally distributed, with a mean life of 4.9 years and a standard deviation of 0.9 years. Using the expanded empirical rule, what is the probability in decimal form that a randomly chosen battery will

(a) last fewer than 4 years?
Answer:

(b) last more than 7.6 years?
Answer:

(c) last between 4.297 and 5.503 years?
Answer: