Four of the six numbers 1867, 1993, 2019, 2025, 2109, and 2121 have a mean (average) of 2008. What is the mean (average) of the other two numbers?
To find the mean of four numbers, I need to add them up and divide by four. So if the mean of four of these numbers is 2008, then their sum must be 4 times 2008, which is 8032. Now I want to find the sum of the other two numbers, so I need to subtract the sum of the four numbers I already have from the sum of all six numbers. To find the sum of all six numbers, I can add them up by pairs, starting from the ends. 1867 + 2121 = 3988, 1993 + 2109 = 4102, and 2019 + 2025 = 4044. The sum of all six numbers is 3988 + 4102 + 4044, which is 12134. So the sum of the other two numbers is 12134 - 8032, which is 4102. The mean of the other two numbers is the sum divided by two, so it is 4102/2, which is 2051. 