Question

A set of data consists of 71 observations. How many classes would you recommend for the frequency distribution?

Answer 1

If k is the number of classes and n is the number of observations, then for number of classes

we should select the smallest k such that $2^k>n$ (2 to k rule).

In our case: $2^6=64<71, \;\;2^7=128>71.$

Thus, 7 classes should be used.