Question 1041635
 A man has had 6 brain scans done, but we only have 5 of his scores:
 The first five scores we have are 27.2,41.6,31.9,0.0, and 13.2.
 We do know his average for the 6 scores was 21.4,
 What was the total score on the missing brain scan?
:
let x = the value for the missing scan
{{{((27.2 + 41.6 + 31.9 + 0 + 13.2 + x))/6}}} = 21.4
add up the values, mutiply both sides by 6
119.9 + x = 6(21.4)
119.9 + x = 128.4
x = 128.4 - 119.9
 x = 8.5 is the missing scan