An education survey published a list of the average student-to-teacher ratio in each of the 50 cities located in a country. If we add the 50 city averages and then divide by 50, we obtain a value of 16.2 students per teacher. Is this value of 16.2 considered the true average for the student-to-teacher ratio for all the classrooms located in the country? Why or why not?

• A. The average should be calculated by taking the median instead of the mean.
• B. Student-to-teacher ratios cannot be averaged because they vary too much.
• C. The national average must be calculated as a weighted mean, not a simple average.
• D. The data includes only 50 cities and excludes smaller towns.

Answer: (C)