Question

The average length of the eight words Betty was asked to spell was 9 letters. The first seven words had the following lengths: 8 letters, 9 letters, 6 letters, 10 letters, 7 letters, 9 letters, and 11 letters. What was the length of the eighth word?

Answer 1

8+9+6+10+7+9+11=60
60/7=8.57
(60+X)/7=9
60+X=63
-60 -60
X=12

Something in my work is wrong but the correct answer is 12 letters