Example 1: A physical education professor wants to study the physical fitness levels of 20,000 students enrolled at her university. She obtains a list of all 20,000 students, numbered from 1 to 20,000 and uses a computer random number generator to generate 100 random integers between 1 and 20,000, then invites the 100 students corresponding to those numbers to participate in the study. Is this a SRS? Explain.