Mean is the "meanest" because it requires the most work. Add up the values in your data set and divide by the number of terms in the data.
Let x represent attendees at Harry's Hoedown, then
Mean = 
41 = 
123 = 48 + 33 + x
123 = 81 + x
42 = x
Answer: 42
I am not sure exactly what you are looking for is this problem. Are you given choices from which to choose?
The empty set is a set with no numbers. Therefore, you should look for a set that doesn't have any elements.
B is rational. B is the correct answer. B is rational.
x^8/x^5=27
x=3 when you flip the equation (rounded number)