1. What is a distribution? How is it related to a histogram?
A distribution is a set of values taken by a variable and how often it takes those values. A histogram is a picture of a distribution.
2. Compute the mean and the median of this list of numbers:
The mean is
To compute the median, sort the list into ascending order and find the number in the middle.
The median is 10.
3. Use the table on the back of this sheet to answer this question: Cholesterol levels for women aged 20 to 34 follow an approximately normal distribution with a mean of 185 and standard deviation of 40. Cholesterol levels above 240 are dangerous and require medical attention. What percent of young women have a cholesterol level above 240?
The first step here is to convert 240 to a z-value via the formula
According to the table, about 0.915 of the population is below this level. That means that roughly 8.5% of the population has a cholesterol level above 240.