A number is missing from the following list: -3,-5, 1, x. ( The missing value is x.) The mean of the list is -1. What is the value of x?
So we have
(-3 + -5 + 1 + x )/ 4 = -1
(-7 + x) / 4 = -1 multiply both sides by 4
-7 + x = -4 add 7 to both sides
x = 3
