Final answer:
Samples are collected at a certain time to monitor population characteristics or make statistical inferences in mathematics and other subjects.
Step-by-step explanation:
In mathematics, samples are often collected at a certain time to monitor population characteristics or to make statistical inferences.
For example, if you want to determine the average height of students in a school, you can collect a sample of students' heights and use that data to estimate the population average. Sampling is a practical technique because it saves time and resources compared to examining an entire population.
Sampling can also be used in other subjects, such as biology, chemistry, and physics, to monitor various factors and conduct experiments.