Consider the number set 10,8,2,13,9. A number is added to the number set which makes the range 15. What could the number be? There are two answers.

-2 or 17

Step-by-step explanation:

The range is the difference between the smallest number and the largest number. Currently, the smallest number is 2 and the largest number is 13.

If we leave 2 as the smallest number, then the new largest number needed for the range to be 15 is:

x - 2 = 15

x = 17

If we leave 13 as the largest number, then the new smallest number needed for the range to be 15 is:

13 - x = 15

x = - 2

The number could be either - 2 or 17.