A group of 20 prisoners in a particular cell block were tested on their knowledge of the rules of the institution. The marks (out of a possible 70) were as follows:

31 28 27 19 18 18 41 0 30 27

27 36 41 64 27 39 20 28 35 30

a. Calculate the range.

b. Remove the largest and smallest scores. Calculate the range for the remaining cases.

c. How do you account for the difference between the values of the above two measures of dispersion?