Question 1181875
The mean is 13 (91/7) words
The mean is the middle of the 7 ordered numbers, or the fourth. It is 10 words.
The sd is 13.28 words.

The typical number of words is 13 for the infants, but the variability is quite large, and the range is from 0 to 40.  Most of the values cluster from 0 to 18 words.