Stratified Sampling: Suppose that the student population below is divided into four strata (base on some criterion). The table lists the students' names and the strata to which they are assigned.

A sample of 70 students is needed.

a) How many students are in each stratum?

b) How many students from each stratum should be selected for a sample?

c) Using stratified sampling method, select an actual sample of 70 students.

there is a spreadsheet with 200 records, not sure how to upload it.