Final answer:
A cluster sample involves randomly selecting restaurants from two cities. A systematic sample involves selecting every nth restaurant from the population.
Step-by-step explanation:
A cluster sample is a sampling technique where the population is divided into clusters, and a random selection of clusters is made. In the context of selecting restaurants from two cities, the procedure would involve randomly selecting two cities and then randomly selecting a sample of restaurants from each city. The random number generator could be used to determine the cities and the specific restaurants within each city.
The systematic sample is a sampling technique where every nth element in the population is sampled. To pick a systematic sample of 15 restaurants, the procedure would involve determining the sample size (15), and then selecting every 15th restaurant from the population. For example, if there are 100 restaurants, the systematic sample would include the 1st, 16th, 31st, 46th, and so on, restaurants.