Question : Calculate the mean from the following table.
Scores | Frequencies |
0-10 | 2 |
10-20 | 4 |
20-30 | 12 |
30-40 | 21 |
40-50 | 6 |
50-60 | 3 |
60-70 | 2 |
Option 1: 33.4
Option 2: 32.6
Option 3: 35.8
Option 4: 34.2
Correct Answer: 33.4
Solution :
The formula for the mean (
The assumed mean (
The midpoints of the score ranges are 5, 15, 25, 35, 45, 55, and 65.
The frequencies are 2, 4, 12, 21, 6, 3, and 2.
Midpoint ( |
Frequency( |
Deviation ( |
|
5 | 2 | –30 | –60 |
15 | 4 | –20 | –80 |
25 | 12 | –10 | –120 |
35 | 21 | 0 | 0 |
45 | 6 | 10 | 60 |
55 | 3 | 20 | 60 |
65 | 2 | 30 | 60 |
|
|
The formula for the mean (
⇒
Hence, the correct answer is 33.4.
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