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 t

Question

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?

Answer 1

 

The average is given by the formulae:

 

27.2 + 41.6 + 31.9 + 0.0 + 13.2 + x

------------------------------------------   =  21.4

                        6

 

where x is the total score on the missing brain scan. It can be re-written as:

 

113.9 + x =  6*21.4

 

113.9 + x = 128.4                     The solution is    x = 14.5