Question 619350
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Hi,
first four tests(80% of grade) were 76%,65%,90%, and 80%   Average = 77.75
student must have an average(the mean) on five tests that is greater than 
or equal to 80% but less than 90% to recieve a final grade of a B
 .80(77.75) + .20x &#8805; .80
               .20x &#8805; 80 - 62.8
                  x &#8805; 17.2/.2
                  x &#8805; 86  ***** B the highest grade possible

              .20x < 90 - 62.8
                 x &#8805; 27.2/.2
                  x &#8805; 138%