Question

bicycles have three types of tires: mountain - bike, road touring, and cruising. an experiment is to be conducted to determine whether the mileage before a tire change is needed is the same for all three types of tires. in previous studies, it was determined that bicycle weight (light, normal, heavy) is associated with frequency of tire changes, but bike type (mountain, road, cruising) is not associated with frequency of tire change. how would blocking best be used? by blocking on bicycle type by blocking on mileage blocking is not suggested by blocking on tire type by blocking on bicycle weight

Explanation:

Blocking in an experiment is used to control for the effects of variables that are not of primary interest but can influence the response variable. Since bicycle weight is associated with the frequency of tire - changes (the response variable of interest here is mileage before tire change), blocking on bicycle weight will help in creating homogeneous groups with respect to this confounding variable. This will allow for a more accurate comparison of the mileage of different tire types.

Answer:

By blocking on bicycle weight