Final answer:
The pattern of scores clustering around the average in a symmetric distribution is known as a Bell curve. This distribution is characterized by a symmetric, bell-shaped pattern where mean, median, and mode coincide, and data spread is described using standard deviations.
Step-by-step explanation:
The pattern of scores usually observed in a variable that clusters around its average is known as a Bell curve. This pattern is characterized by a symmetric, bell-shaped distribution where the mean, median, and mode are all located at the same point. According to the Empirical Rule, approximately 68 percent of the data is within one standard deviation of the mean, approximately 95 percent is within two standard deviations, and more than 99 percent is within three standard deviations, provided the distribution of the data is bell-shaped and symmetric.
An example of a bell curve can be seen in the interpretation of IQ scores, where the mean score is typically set to 100 and scores are spread out according to standard deviations. A standard deviation of 15 points implies that a score of 115 is one standard deviation above the mean, while a score of 70 is two standard deviations below the mean.