I believe that the common difference would be.10
Divide until you get one moth alone then multiply then simplify if you don't know how to simplify please pm me.
The mean book rating will decrease
Add all the numbers together:
5 + 5 + 6 + 7 + 7 + 7 + 7 + 8 + 8 + 8 + 9 + 9 + 10 + 10 + 10 + 10 + 10= 136
divide the total with the total amount of numbers
136/17 = 8
Now add all the numbers again WITH the one
5 + 5 + 6 + 7 + 7 + 7 + 7 + 8 + 8 + 8 + 9 + 9 + 10 + 10 + 10 + 10 + 10 + 1= 137
Divide the total amount with the amount of numbers there are
137/18 = 7.61
7.61 < 8
The mean book rating will decrease by 0.39
hope this helps
3+16=19,
3+20=23
So the correct answer would be 19 and 23