To estimate the percentage of defects in a recent manufacturing batch, a quality control manager at Toyota selects every 19th car that comes off the assembly line starting with the ninth until she obtains a sample of 120 cars.

What type of sampling is used?

(a) Simple random

(b) Systematic

(c) Cluster

(d) Convenience

(e) Stratified

Answer: Systematic

Explanation: It refers to a method of sampling in which the samples are selected from a population randomly but as per a set criteria and defined interval. The interval is computed by dividing the population with the sample size needed.

In the given case, the quality manager starts taking sample on the on a fixed interval, that is, every 19th car after the ninth car.

Hence from the above we can conclude that the correct option is B.