Mean - This is the average value of a set of numbers.

In the case of problem #1, your numbers are 7, 9, 5, 3, 15, 15. There are 6 numbers all together right? This is important to know.

To find the mean you must add all of the numbers together, and divide by how many there.

7 + 9 + 5 + 3 + 15 + 15 = 54

54/6= 9

The mean is 9.

Example:
 
It is often necessary to calculate the mean of something in a school or work environment. Knowing how to do so is very important. The mean, or mean average, of a set of numbers is often helpful within other mathematical processes. The process is quite simple, and easily mastered. 

Steps

1. Determine to the set of numbers you want to find the mean of.
   
   
   • Example: 2,3,4,5,6.
2. Add those numbers together to find the sum. Make sure calculations are accurate!
   
   • Example: 2+3+4+5+6=20.
3. Determine the quantity of numbers in your group.
   
   
   • Example: 2,3,4,5, and 6 are the 5 separate numbers of which an average is desired.
4. Divide the sum of the numbers (20) by the amount of numbers (5).
   
   
   • Example: 20÷5 = 4
     Therefore 4 is the mean of the numbers.

   Tips

   • The mean is easy as you add up all the figures and divide by how many figures there are.