A point is usually marked by a dot and a capital letter. Sample of size n. Lower first quartile.
Conclusions are made about the quality of goods being manufactured in a factory after inspectors carefully examine a sample of the goods to decide whether the quality is satisfactory.
Upper third quartile. There are two types of estimates. You ask 100 randomly chosen people at a football match what their main job is. And then we can calculate a statistic from that sample based on that sample maybe we picked n balls from there.