A classroom of n = 10 children has a mean score of 17.200 on a measure of hyperactivity. One new child is added to the class, and the mean hyperactivity score for the resulting classroom including all the children is 18.000. Find the value of the new child's hyperactivity score.

Question

How would I figure this out?
The new n = 11
New score is 18.000
That's about as much as I could figure out.

Answer 1

child-- c
c + 17.20(10) = 18.00(11)
c + 172 = 198
c + 172 -172 = 198 - 172
c = 26

Answer 2

Thank you so much! I had already asked this question before but they never explained to me how they got the 198. I really appreciate.