Here are 10 test scores: 30, 74, 76, 77, 78, 79, 80, 80, 82, 84. The mean of these scores is 74. Does this set have an outlier and, if so, how does removing it affect the mean?

Question

jadeishere · Answer

well notice how all of the numbers are in the 70's or 80's? and then there's that one awkward '30' in the data set. That's your outlier. Outliers are numbers that don't fit with the set of values given. If you were to take out that outlier, the mean would change.

jadeishere · Answer

so if the mean is 74 currently, and we know a mean is the sum of all of the values divided by the number of values in the set then if we take away 30, then it'll be..
74 + 76 + 77 + 78 + 79 + 80 + 80 + 82 + 84 = x / 9

jadeishere · Answer

then it'd be 71.44444444 so round that and it'd be 71 as the mean.