The mean of the data set 1, 3, 5, 7, and 9 is _______.

Question Analysis
This question tests the student's ability to calculate the mean of a given data set. The mean is the sum of all data points divided by the number of data points.

Key Concept Explanation
The mean is a measure of central tendency that represents the average value of a data set. It is calculated by summing all the data points and then dividing by the number of data points.

Step-by-step Solution
1. Sum the data points: