Size of item | 3.5 | 4.5 | 5.5 | 6.5 | 7.5 | 8.5 | 9.5 |
Frequency | 3 | 7 | 22 | 60 | 85 | 32 | 8 |
A) 1.29
B) 2.19
C) 1.32
D) none of these
Correct Answer: C
Solution :
Let the assumed mean be A=6.5 Calculation of varianceSize of item \[({{x}_{i}})\] | \[{{f}_{i}}\] | \[{{d}_{i}}=\] \[{{x}_{i}}-6.5\] | \[{{d}_{i}}^{2}\] | \[{{f}_{i}}{{d}_{i}}\] | \[{{f}_{i}}{{d}_{i}}^{2}\] |
3.5 | 3 | -3 | 9 | -9 | 27 |
4.5 | 7 | -2 | 4 | -14 | 28 |
5.5 | 22 | -1 | 1 | -22 | 22 |
6.5 | 60 | 0 | 0 | 0 | 0 |
7.5 | 85 | 1 | 1 | 85 | 85 |
8.5 | 32 | 2 | 4 | 64 | 128 |
9.5 | 8 | 3 | 9 | 24 | 72 |
\[N=\sum \] \[{{f}_{i}}=217\] | \[\sum {{f}_{i}}{{d}_{i}}\] \[=128,\] | \[a\sum {{f}_{i}}{{d}_{i}}^{2}\] \[=362\] |
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