No formula is associated with this problem.
Work Step by Step
a.) The three randomly chosen pediatric clinics in the United States are the three selected clusters (not all clinics are selected), meaning the sampling is cluster sampling. b.) Simple Random Sampling c.) Stratified Random Sampling since the different altitudes represent the strata. d.) Simple Random Sampling or two-stage cluster sampling with the 20 vines being the clusters selected e.) Stratified Random Sampling because the three breed types are the strata.