Percentiles and Box Plots · Superchallenge problem

A whole number $x$ with $1 \le x \le 50$ is added to the data $2, 9, 10, 11, 12, 13, 21$, making eight values. Quartiles are the medians of the lower four and upper four values, and outliers use the $1.5 \cdot \text{IQR}$ rule. For how many values of $x$ does the new data set contain at least one outlier?