What does Interquartile range mean

The interquartile range (IQR) is a measure of variability, based on dividing a data set into quartiles. Quartiles divide a rank-ordered data set into four equal parts. The values that divide each part are called the first, second, and third quartiles;

the answer is c: divide the arc's degree measure by 360°, then multiply by the circumference of the circle.