3.12 Decide whether these sampling methods produce a simple random sample of students from a class of 30 students. If not, explain why not.

a Select the first six students on the class roll sheet.

b Pick a digit at random and select those students whose phone number ends in that digit.

c If the classroom has six rows of chairs with five seats in each row, choose a row at random and select all students in that row.

d If the class consists of 15 males and 15 females, assign the males the numbers from 1 to 15 and the females the numbers from 16 to 30. Then use a random digit table to select six numbers from 1 to 30. Select the students assigned those numbers for your sample.

e If the class consists of 15 males and 15 females, assign the males the numbers from 1 to 15 and the females the numbers from 16 to 30. Then use a random digit table to select three numbers from 1 to 15 and three numbers from 16 to 30. Select the students assigned those numbers for your sample.

f Randomly choose a letter of the alphabet and select for the sample those students whose last name begins with that letter. If no last name begins with that letter, randomly choose another letter of the alphabet.