please break this problem down to laymen term so that I understand how you arrived at the answer.
1. AllElectronics caries 1000 products, P1, … P1000. Consider customers Ada, Bob, and Cathy such that Ada and Bob purchase three products in common, P1, P2, and P3. For the other 997 products, Ada and Bob independently purchase seven of them randomly. Cathy purchases 10 products, randomly selected from the 1000 products. In Euclidean distance, what is the probability that dist(Ada, Bob) > dist(Ada, Cathy)? What if Jaccard similarity (Chapter 2) is used? What can you learn from this example? (Problem 11.2, Page 539-)
Book:
Data Mining: Concepts and Techniques, 3rd Edition
Problem 11.2, Page 539