What is the mean of all three-digit positive integers whose digits are in the set {2,0,1,9}?
Sum =(102, 109, 120, 129, 190, 192, 201, 209, 210, 219, 290, 291, 901, 902, 910, 912, 920, 921) =7728
There are 18 integers. So, the mean =7728 / 18 =429 1/3 - the mean.
