In which type of statistical distribution are the mean, median, and mode equal?

The mean, median, and mode are all equal in a normal distribution due to its symmetrical shape. In a normal distribution, the data is evenly distributed around the mean, which means that half of the data points lie to the left and half lie to the right. As a result, the measures of central tendency (mean, median, and mode) coincide at the center of this distribution.

In contrast, a nonnormal distribution does not have this property. It could be skewed either to the left or to the right, causing the mean, median, and mode to differ from each other. A simple distribution does not specifically describe a statistical shape and does not inherently imply that these measures are equal. A bimodal distribution, characterized by having two distinct modes, typically does not have equal mean, median, and mode due to the presence of the two peaks in the data set.

Thus, the normal distribution is uniquely defined by the equality of these three statistical measures, making it the correct choice.