An instructor gives 3 initial exams and a final exam for a certain course. The average of 3 initial exams are weighted 3/5 and the final exam is weighted 2/5. A student received initial exam grades 72,73 and 80 and a final grade of X. If the student's weighted average for the course was 79, what is the value of X? please explain the answer.
From the marking scheme,
Weighed average = (x1 + x2 + x3 + 2x4)/5
79 = (72 + 73 + 80 + 2x4) / 5
(395 - 72 - 73 -80)/2 = x4 = 85
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