Final answer:
When exam scores are positively skewed, it means that most students scored below the average, with a few high scores pulling the mean upwards.
Step-by-step explanation:
When a professor finds that the scores on an exam are positively skewed, it indicates that there is a longer tail on the right side of the distribution, meaning that a majority of students performed below average. This can be visualized through a histogram where the tail stretches towards the higher scores, but most of the data is clustered towards the lower end of the scale. In a positively skewed distribution, the mode and median will be less than the mean, and the skew is caused by a small number of students scoring much higher than the rest.
In the context of exam scores, a positive skew suggests that while some students may have done exceptionally well, elevating the mean score, the more frequent scores are lower, thus the peak of the distribution is towards the lower end. This situation can reflect various scenarios such as a challenging exam where few students excelled or extra credit opportunities that only a minority of students took advantage of.