4. the ages of a group of 9 friends are: 12, 14, 13, 16, 13, 15, 15, 17 and 13. calculate the mean, median and range

 Mean = Average

12 + 14 + 13 + 16 + 13 + 15 + 15 + 17 + 13 = 128

There are 9 numbers

128 / 9 = 14.2

Mean = 14.2

Median: The mddle number

First, order the numbers

12, 13, 13, 13, 14, 15, 15, 16, 17

The middle number is 14

Median = 14

Range: Highest # - Lowest #

Highest = 17
Lowest = 12

17 - 12 = 5

Range = 5

Hope this helped
Have a great day :)