In Poland students are required to achieve a score of 21 or

In Poland students are required to achieve a score of 21 or higher on the high-school Polish language “maturity exam” to be eligible for university. The following graph shows the frequency distribution of scores.

Examine the graph and identify the most conspicuous pattern in these data

Solution

From a general guess, if scores are approximately normally distributed, the frequencies should be smothly tapered everywhere. From the given graph, this is confirmed except at point 21. The frequency drops raipidly just below 21 and increases rapidly just after 21.

Some students made more score then they had, and jumped from below 21 to above 21. It seems that \"grace marks\" were given to some students whose scores were ljust below 21, in order to push them above 21 to be eligibile in the university.