Which of the following are correct?
(A) In simple random sampling, every member of the population has an equal chance of being included in the sample.
(B) Selecting only the students whose roll numbers end with the digit 2 is simple random sampling.
(C) In systematic random sampling, after a random starting point, members are chosen at regular intervals from an ordered list.
(D) A sample made up only of conveniently available people is likely to be biased.
Choose the correct answer from the options given below:
Answer & explanation
Correct answer: option 2
The correct answer is Option (2) → (A), (C) and (D) only
In simple random sampling every member has an equal chance of selection, entirely by chance. In systematic random sampling members are taken at a fixed interval from an ordered list after a random start. A sampling process that favours some members over others is biased.
So a rule that leaves some members out (like roll numbers ending in 2) is not simple random sampling, and a convenience sample is biased.
Checking the statements
(A) In simple random sampling, every member of the population has an equal chance of being included in the sample. — Correct. This is what simple random sampling means.
(B) Selecting only the students whose roll numbers end with the digit 2 is simple random sampling. — Incorrect. Students with other last digits have no chance of selection.
(C) In systematic random sampling, after a random starting point, members are chosen at regular intervals from an ordered list. — Correct. For example 2, 5, 8, 11 with interval 3.
(D) A sample made up only of conveniently available people is likely to be biased. — Correct. Convenience sampling is a biased method.