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 with step deviation method
Number of 0 – 6, 6 – 10 ,10 – 14, 14 – 20, 20 – 28, 28 – 38, 38 – 40
days
Number of 11, 10, 7, 4, 4 ,3, 1
students
Step-by-step explanation:
To find the class mark (x i ) for each interval, using the following relation:
(x i ) = Upperclasslimit+Lowerclasslimit
2
Taking 17 as assumed mean (a), calculating di
and fi d i as:
From the table:
∑fi = 40
∑fi di = −181
Mean, xˉ = a+ ∑fi di
∑fi
= 17 + ( – 181 )
40
=17−4.525
=12.475
≈12.48
Therefore, the mean number of days =12.48 days for which a student was absent.
Answer:
12.48 days
Step-by-step explanation:
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