In that distribution, which class interval contains the mode?

In that distribution, which class interval contains the mode?

• A. 5-9
• B. 10-14
• C. 15-19
• D. 20-24

Answer: (C)

The idea here is finding the modal class—the interval that contains the most observations. In a grouped distribution, you identify the mode by looking for the class with the highest frequency (or, if the class widths aren’t the same, the highest frequency density, which is frequency divided by the class width). In this distribution, the 15–19 interval has the most data points, so it is the tallest, meaning the most observations fall there. That interval therefore contains the mode. The other intervals have fewer observations, so they don’t represent the peak of the distribution. If the class widths were different, you’d compare frequency densities instead of raw frequencies to determine the modal class.

The idea here is finding the modal class—the interval that contains the most observations. In a grouped distribution, you identify the mode by looking for the class with the highest frequency (or, if the class widths aren’t the same, the highest frequency density, which is frequency divided by the class width).

In this distribution, the 15–19 interval has the most data points, so it is the tallest, meaning the most observations fall there. That interval therefore contains the mode.

The other intervals have fewer observations, so they don’t represent the peak of the distribution. If the class widths were different, you’d compare frequency densities instead of raw frequencies to determine the modal class.