1. A survey was conducted to measure the height of ment. In the survey, respondents were grouped by age. In the 20-29 age group, the heights were normally distributed, with a mean of 68.7 inches and a standard deviation of 3.0 inches. A study participant is randomly selected.
a) Find the probability that his height is less than 68 inches.
b) Find the probability that his height is between 68 and 71 inches.
c) Find the probability that his height is more than 71 inches.
(Round to four decimal places.)
2. The life span of a battery is normally distributed, with a mean of 2300 hours and a standard deviation of 50 hours. What percent of batteries have a life span that is more than 2365 hours? Would it be unusual for a battery to have a lifespan that is more than 2365 hours?