Jeff's five assignment scores are 89, 92, 88, 95 and 91. What is the arithmetic mean of these five scores?
To find the arithmetic mean of a set of numbers, I need to add up all the numbers and divide by how many there are. In this case, I have five numbers, so I will add them up and divide by five. I can use a calculator or do it by hand. I will do it by hand because it is not too hard. I will put the numbers in pairs that add up to 180 or 190, like this: 89 + 91, 92 + 88, and 95. Now I have three numbers that add up to 455: 180 + 180 + 95 = 455. Finally, I divide by five to get the mean: 455 / 5 = 91. So the arithmetic mean of Jeff's five assignment scores is 91. 