Question

Calculate Jane's weighted grade: (round to the nearest tenth)

Portion of Grade Jane's Averages
Homework 15%. 67
Labs 10% 98
Quiz 25% 75
Test 50% 95

Answer 1

15 * 67 + 10 * 98 + 25 * 75 + 50*95 = 100 * x
100 x = 1005 + 980 + 1875 + 4750
100 x = 8610
x= 86.1

Answer 2

for a straight average, you just add up the scores and divide by how many scores there are.
For a weighted average, you multiply each score by its weight (% of grade)
So, in this case, that is
(0.15*67 + 0.10*98 + 0.25*75 + 0.50*95) = 86.1

Note that the regular mean is just a special case of a weighted average, where each value is weighted by 1/4

(67+98+75+95)/4 = 1/4 *67 + 1/4*98 + 1/4*75 + 1/4*95