The printing department of a publishing company wants to determine whether there are differences in durability between three types of book bindings. Twenty-five books with each type of binding were selected and placed in machines that continually opened and closed them. The numbers of openings and closings until the pages separated from the binding were recorded.

a. What techniques should be considered to determine whether differences exist  between the types

of bindings? What are the required conditions? How do you decide which technique to use?

b. If we know that the number of openings and closings is not normally distributed, test to determine whether differences exist between the types of bindings.