A set of 5 numbers has a mean of 12 and a median of 10. If a new number, 18, is added to the set, what is the new mean of the 6 numbers?

✓ Correct Answer: Option C

The initial sum of the 5 numbers is 5 * 12 = 60. When 18 is added, the new sum becomes 60 + 18 = 78. The new mean is the sum divided by the new count of numbers: 78 / 6 = 13.