A company has developed a new engine whose average lifetime is unknown. In order to estimate this average, 100 engines are rando
mly selected from a large production line and tested; their average lifetime is found to be 11 years. The 11 years represents a:a. parameter.b. statistic.c. sample.d. population.
A statistic is defined as a metric derived from (or that describes) a sample. As such, given a certain population (in the case of the question, <em>the population is the total number of new engines developed by the company</em>), a sample can be selected from the population (<em>the sample in the question is the 100 engines that are randomly selected</em>).
Any characteristic that describes the population is known as a parameter, whereas a characteristic that defines the sample is a statistic. In the question given, the average lifetime of 11 years was derived from the sample of 100 engines as is thus a statistic.
