Answer:
Step-by-step explanation: Hello! You know that there are 3 students who scored 55, 4 students who scored 60, 8 students who scored 65, 4 students who scored 70, 4 students who scored 75, 1 student who scored 80, 9 students who scored 85, and 5 students who scored 90. To find the mean of a set of values, here is the formula:
a + b + c + d + e . . .
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2
Each variable should represent the score of a single student, so write each score for each individual student.
(55 + 55 + 55 + 60 + 60 + 60 + 60 + 65 + 65 + 65 + 65 + 65 + 65 + 65 + 65 + 70 + 70 + 70 + 70 + 75 + 75 + 75 + 75 + 80 + 85 + 85 + 85 + 85 + 85 + 85 + 85 + 85 + 85 + 90 + 90 + 90 + 90 + 90)/2
You could divide all of this by 2 or you could multiply the values and then add them:
((55 x 3) + (60 x 4) + (65 x 8) + (70 x 4) + (75 x 4) + 80 + (85 x 9) + (90 x 4))/2
Either way works, but the second way is probably faster.
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How to find the answer:
55 x 3 = 165
60 x 4 = 240
65 x 8 = 520
70 x 4 = 280
80 = 80
85 x 9 = 765
90 x 4 = 360
Substitute this into the equation
(165 + 240 + 520 + 280 + 80 + 765 + 360)/2
(405 + 800 + 845 + 360)/2
(1205 + 1205)/2
2410/2
= 1205
The answer is 1205