Answer:
-8
Step-by-step explanation:
Use the mean formula:
mean = sum of elements / number of elements
Let x represent the 8th number, and plug this and the other numbers into the formula:
(9 + 2 + 3 + 4 + 12 + 13 + 1 + x) / 8 = 4.5
Simplify and solve for x
(44 + x) / 8 = 4.5
44 + x = 36
x = -8
So, the 8th number is -8
