One indicator of an outlier is that an observation is more than 2.5 standard deviations from the

Question:

One indicator of an outlier is that an observation is more than 2.5 standard deviations from the mean. Consider the data value 80.
(a) If a data set has mean 70 and standard deviation 5, is 80 a suspect outlier?
(b) If a data set has mean 70 and standard deviation 3, is 80 a suspect outlier?