Given the set: # {-6,x,7,11,29,-4,-5} #, for what x would the mean of the set be -9?

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Answer 1 · 2015-12-11T08:57:12

#color(white)(xx)x=-95#

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

#color(white)(xx)-9=1/7sum_(i=1)^7 a_i#
#=>(-6+x+7+11+29-4-5)/7=-9#

Multiply both sides by #7#
#color(white)(xx)color(red)(7*)(-6+x+7+11+29-4-5)/7=color(red)(7*)(-9)#
#=>x+32=-63#

Add #-32# to both sides
#color(white)(xx)x+32color(red)(-32)=-63color(red)(-32)#
#=>x=-95#