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# A class teacher has the following absentee record of 40 students of a class for the whole term. Find the mean number of days a student was absent. Number of days 0-6 6-10 10-14 14-20 20-28 28-38 38-40 Number of students 11 10 7 4 4 3 1

 Class interval Frequency $$(f_i)$$ Mid-point $$(x_i)$$ $$f_i x_i$$ 0-6 11 3 33 6-10 10 8 80 10-14 7 12 84 14-20 4 17 68 20-28 4 24 96 28-38 3 33 99 38-40 1 39 39 $$\sum f_i \ = \ 40$$ $$\sum f_i x_i \ = \ 499$$

The mean formula is,

$$\overline{x} \ = \ \frac{ \sum \ f_i x_i}{ \sum f_i}$$

$$= \ \frac{499}{40}$$

$$= \ 12.48$$ days

$$\therefore$$ The mean number of days a student was absent = 12.48.