Question

Marie scored 95,86 and 89 on three science tests she wants her average score for 6 test to be at least 90 what inequality can you write to find the average scores that she can get on her next three test to meet this goal? Use s to represent the lowest average score

Answer 1

(3s + 270) / 6 > 90

s = 90; lowest average score

95+86+89 = 270

(3s + 270) / 6    >    90 
                * 6          * 6
3s + 270          >     540
     - 270                 -270
3s                    >     270
÷3                             ÷3
  s                    >       90

To check: 

(3s + 270)/6     > 90
(3(90) + 270)/6 > 90 
(270 + 270)/6   > 90
540 / 6             > 90
90                    > 90