Outlier An extreme value in a set of data which is much higher or lower than the other numbers. ... Outliers affect the mean value of the data but have little effect on the median or mode of a given set of data. Your question asks how number 42 would affect the mean, that depends on two things, is the 42 higher or lower than the mean before 42 is added to the data? If the 42 is higher, the mean would increase, if the 42 is lower, the mean would decrease. Hope that helps.
