Find the mean number of days a student was absent.
Class 10 NCERT Maths Chapter 14
NCERT Book Page No. 271
Exercise 14.1 and Question No. 8
A class teacher has the following absentee record of 40 students of a class for the whole term.
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To find the class mark of each interval, the following relation is used.
xᵢ = (Upper Limit + Lower Limit)/2
Taking 17 aa assumed mean (a), dᵢ and fᵢdᵢ are calculated as follow.
From the table, we obtain
∑fᵢ = 40 + f, ∑fᵢdᵢ = -181 and a = 17
mean (X̄) = a + (∑fᵢdᵢ / ∑fᵢ) = 17 + (-181/40) = 17 – 4.525 = 12.475 = 12.48
Therefore, the mean number of days is 12.48 days for which a student was absent.