Okay I need help. I'm studying for a test, and I keep trying to do this problem over and overrr.

This is the table.

Classes ---- Frequency

10-13 ---- 1

14-17 ---- 0

18-21 ---- 15

22-25 ---- 7

26-29 ---- 2

I keep getting 7.93 but my answer sheet says it's supposed to be 3.2! (Headbang)

What am I doing wrong?

I would post my work but I don't know how to (Lipssealed).

Thanks in advance! (Hi)