A survey was conducted to determine how many movies were seen in one month among the 26 students in Mrs. Hampton’s sixth-grade class. The results are shown in the dot plot below.

I need help for these parts of the problem -

c) Calculate the measures of spread for Mrs. Hampton’s class data. Justify your response by describing the process used to find each measure.

d) Which is a better measure of spread: range or interquartile range? Why?