Rearrange the numbers in order from least to greatest:
6, 1, 5, 2, 6, 5, 2, 6, 5
1, 2, 2, 5, 5, 5, 6, 6, 6
The number 1 is used once. The number 2 is used twice. Numbers 5 and 6 are used three times.
The mode is the number that is represented most in a set of numbers. Since 5 and 6 are both represented three times, these numbers will be the mode for this set.
The answers are C. 5 and D. 6.
