Final answer:
A parameter is a numerical measurement of a population, and a statistic is a numerical measurement of a sample. The 50 percent figure from a survey of high school seniors about their post-graduation plans is an example of a statistic.
Step-by-step explanation:
A parameter and a statistic differ in that a parameter is a numerical characteristic of an entire population, whereas a statistic is a numerical characteristic of a sample taken from that population. For example, if we were to calculate the average height of all students in a school, that average would be a parameter because it includes the entire population of interest. However, if we calculate the average height of students in a single classroom of that school, that average would be a statistic as it represents a sample of the entire school population.
In the given scenario where the U.S. federal government conducts a survey of high school seniors and finds that fifty percent are planning to attend a four-year college or university in the following year, that fifty percent figure is an example of a statistic because it is likely derived from a sample of the entire population of high school seniors.