for #1
city A's mean would be 10.5, then you would divide it by the number of numbers there is which is 5,So 10.5/5 is 2.1
city B's mean would be 11.6 then you would divide it by the number of numbers there is which is 5, So 11.6/5 is 2.32.
thats all I have don't know how to do #3 sorry
