The data below shows the average number of text messages sent daily by a group of people: 7, 8, 4, 7, 5, 2, 5, 4, 5, 7, 4, 8, 2, 1, 8 what will be the effect of introducing an outlier in the data? a. the median number of text messages sent daily will increase. b. the median number of text messages sent daily will decrease. c. the difference between the maximum and minimum number of text messages sent daily will increase. d. the difference between the maximum and minimum number of text messages sent daily will decrease.

It all depends. You've given us an incredibly vague question.

The outlier could be a number that's low or quite high. Also, outliers
shouldn't really contribute towards the value of the mean, median or 
range related to a group of data.

They are called outliers because they are bizarre results or numbers
and should be detached from groups of data. Outliers by definition
are abnormalities or anomalies.

I'd say outliers don't really change anything, unless you actually want
to give them credibility or weight.

Large outliers can inflate the value of means, medians and ranges.

Small outliers will invariably deflate the value of means and medians.