Given a set {-3,2,-1,x} {3,2,1,x}, for what x would the mean of the set be -5?

1 Answer
Jan 5, 2016

x=-18x=18

Explanation:

mean=(Sigmax_i)/n

or, "the sum of all the elements divided by the number of elements"(as we're talking about a set here.)

We already know the mean is -5, and there are 4 elements: -3, 2, -1, and x.

So adding together all our elements and dividing by how many there are, should give us a mean of -5. We will therefore end up with an equation which we can solve for x.

-5=(-3+2-1+x)/4

so
x-2=-20

x=-18