Question 872850
given that the nine numbers 16, w, 17, 9, x, 2, y, 7 and z have a mean of 11, find the mean of w,x,y and z
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"the nine numbers 16, w, 17, 9, x, 2, y, 7 and z have a mean of 11", so this means



(16 + w + 17 + 9 + x + 2 + y + 7 + z)/9 = 11



(51 + w + x + y + z)/9 = 11



51 + w + x + y + z = 11*9



51 + w + x + y + z = 99



w + x + y + z = 99-51



w + x + y + z = 48



The sum of w,z,y,z is 48. So the average of the 4 values is 



(w + x + y + z)/4 = 48/4



(w + x + y + z)/4 = <font size=4 color="red">12</font>