The average of n numbers is 80. One of the numbers is 100. After removing the number 100, the average becomes 78. What is value n?
The original total of the numbers will be 80 n
then remove one number, 100 and the average becomes 78
the new total will be 78 (n-1) which is 100 less than the old total 80 n
soo 78 (n-1) = 80n - 100
78n-78 = 80n - 100
22 = 2n