For a population of 2,500 students (500 students for each year, from first to fifth year), a sample of size 100 students needs to be taken.

Indicate what type of sampling is carried out in each case.

Each student writes their name on a piece of paper, puts it in a bag, and the principal chooses 100 papers.

Each student is assigned a number between 1 and 2,500 and are selected by generating 100 random four-digit numbers using a computer program.

For each year a number is assigned to each student between 1 and 500, and 1 out of 25 students is chosen.

A division is randomly chosen from each of the years and 20 students are selected from each division.

60 students from the first 3 years and 40 students from the last two years are chosen at random

60 students from the first 3 years and 40 students from the last two years are chosen at random. Men and women are selected separately according to the proportion of women and men in the school.