A certain characteristic in a large population has a distribution that is symmetric about the mean m. 64 percent of the distribution lies within one standard deviation d of the mean. If the shelf’s average life is 7.8 years and the standard deviation is 2.4 years, what percent of the distribution has more than 10.2 years as a shelf’s average life?  Choose the correct choice from the following.
A) 15% B) 16% C) 17% D) 18% E) 19%
Average = 7.8   SD = 2.4   7.8 - 2.4 &lt; 64% of distribution &lt; 7.8 + 2.4   5.4 &lt; 64% of distribution &lt; 10.2   36% is outside this range.   Given: Distribution is symmetric. So 18% of distribution is less than 5.4 and the other 18% of distribution is greater than 10.2.   Answer: 18%
<result>D</result>
A certain characteristic in a large population has a distribution that is symmetric about the mean m. 64 percent of the distribution lies within one standard deviation d of the mean. If the shelf’s average life is 7.8 years and the standard deviation is 2.4 years, what percent of the distribution has more than 10.2 years as a shelf’s average life?