- (a) All measures exist.
- (b) The affected measure is Mean.
- (c) The affected measures are Mean and Median.
Thus, the answers are:
- (a): \(\text{All of these measures exist}\)
- (b): \(\text{Mean}\)
- (c): \(\text{Mean, Median}\)
\(\boxed{\text{(a): All of these measures exist, (b): Mean, (c): Mean, Median}}\)