At an airport screening, every 4th passenger will be selected to have their hands swabbed to screen for traces of explosives. Which sampling method is being used


  1. The sampling method used is classified as Systematic.

    How are sampling strategies classified?

    Samples may be classified as:
    • Convenient: Drawn from a conveniently available pool.
    • Random: All the options into a hat and drawn some of them.
    • Systematic: Every kth element is taken.
    • Cluster: Divides population into groups, called clusters, and each element in the cluster is surveyed.
    • Stratified: Also divides the population into groups. Then, a equal proportion of each group is surveyed.
    In this problem, every 4th element is taken, which is a systematic sample with k = 4.
    More can be learned about sampling at


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