Question

The first quartile of a data set is 18, the median is 25, the third quartile is 28,

Answer 1

The outlier would be shown as a dot so the answer is B. 45
The interquartile range is 28 - 18 = 10
A simple rule is that points more than 1.5xIRQ above or below the medians is an outlier and is shown as a point.
28 + 1.5x10 = 43. 45 is above this value.