Answer:
1. 18
2. 8
Explanation:
the mean is calculated by:
total / number of values
the current total is
10 + 14 + 8 + 16 + 12 = 60
now when we add another number there will be 6 numbers and we want the mean to be 13 so:
total / 6 = 13
total = 13 × 6
total = 78
but our current total is 60
so the missing number is 78 - 60 = 18
for part 2:
if we remove a number there will be 5 values and we want the mean to be 14 so:
total / 5 = 14
total = 14 × 5
total = 70
but we have the total of 6 numbers as 78 so we have to remove 78 - 70 = 8