Astudent conducts a survey to determine which students at the high school completed an algebra course during their freshman year. 49, 34, and 48 students are selected at random from the sophomore, junior, and senior classes. each class has a population of 496, 348, and 481 respectively. which type of sampling did the student use?
random
stratified
systematic
cluster

The type of sampling done on the students is

STRATIFIED

Since the population are divided into strata (groups) according to their year level and random samples are taken from each of the stratum.

Random sampling is done when the samples are randomly taken from all the population. Systematic sampling is done when there is an interval used to determine which sample is to be taken. Cluster sampling is done when the population is grouped into cluters and samples are taken from random clusters. Cluster sampling does not ensure that samples will be taken from all clusters.