For the month of February, a class teacher of Class IX has the following absentee record for 45 students- Find the mean number of days, a student was absent. | ||||||
Number of days of absent | 0 ? 4 | 4 ? 8 | 8 ? 12 | 12 ? 16 | 16 ? 20 | 20 ? 24 |
Number of students | 18 | 3 | 6 | 2 | 0 | 1 |
Answer:
C.I. \[{{f}_{i}}\] \[{{x}_{i}}(mid-value)\] \[d={{x}_{i}}-A\] \[{{f}_{i}}\times {{d}_{i}}\] 0 ? 4 18 2 \[12\] \[216\] 4 ? 8 3 6 \[8\] \[24\] 8 ? 12 6 10 \[4\] \[24\] 12 ? 16 2 A=14 0 00 16 ? 20 0 18 4 00 20 ? 24 1 22 8 08 \[\sum{{{f}_{i}}=30}\] \[\sum{{{f}_{i}}{{d}_{i}}=-256}\] \[Mean=A+\frac{\sum{{{f}_{i}}{{d}_{i}}}}{\sum{{{f}_{i}}}}\] \[=14+\left( \frac{-256}{30} \right)\] \[=14-8.53\] \[=5.47\]
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