Question

the mean of of seven numbers is 81 . if one of the number is discarded. then the new mean of the remaining numbers is 78. fine the number which got discarded

Answer 1

mean=total/count
total of seven=81*7
total of six=78*6
total of seven = total of six+discarded

Answer 2

x/7=81
x=567
then
567-y (the no. discarded)/6=78
y=99