Given a set {-2,x,-3,-4,1,15,22,2} , for what x would the mean of the set be -12?

1 Answer
Dec 28, 2015

x=-127

Explanation:

color(white)(xx)bar a =1/nsum_(i=1)^n a_i (the mean of a set of n data points)

color(white)(xx)-12=1/8sum_(i=1)^8 a_i
=>(x-4-3-2+1+2+15+22)/8=-12

Multiply both sides by color(red)8
color(white)(xx)color(red)(8xx)(x-4-3-2+1+2+15+22)/8=color(red)(8xx)-12
=>x+31=-96

Add color(red)(-31) to both sides
color(white)(xx)x+31color(red)(-31)=-96color(red)(-31)
=>x=-127