NCERT Class XI Mathematics - Statistics - Solutions
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Question : 18
Total: 34
Find the mean and standard deviation using short-cut method.
| | 60 | 61 | 62 | 63 | 64 | 65 | 66 | 67 | 68 |
|---|---|---|---|---|---|---|---|---|---|
| | 2 | 1 | 12 | 29 | 25 | 12 | 10 | 4 | 5 |
Solution:
| | | | | |
|---|---|---|---|---|
| 60 | 2 | -4 | - 8 | 32 |
| 61 | 1 | -3 | - 3 | 9 |
| 62 | 12 | - 2 | - 24 | 48 |
| 63 | 29 | - 1 | -29 | 29 |
| 64 | 25 | 0 | 0 | 0 |
| 65 | 12 | 1 | 12 | 12 |
| 66 | 10 | 2 | 20 | 40 |
| 67 | 4 | 3 | 12 | 36 |
| 68 | 5 | 4 | 20 | 80 |
| 100 | 0 | 286 |
Let assumed mean (A) = 64; Mean
S.D. (σ) =
=
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