(CBSE 2006
r. The mean of the following distribution is 53. Find the value off:
Class 0-20 20-40 40-60 60-80
Frequency
17
28
32
fi
1. Find the mean of the following frequency distribution:
80-100
19
[CBSE 2006
Answers
Answered by
0
Answer:
Step-by-step explanation:Calculation of Mean
Classes Mid-values
(x
i
) Frequency
(f
i
) d
i
=x
i
−50 u
i
=
20
x
i
−50
f
i
u
i
0-20 10 15 -40 -2 -30
20-40 30 18 -20 -1 -18
40-60 50 21 0 0 0
60-80 70 29 20 1 29
80-100 90 17 40 2 34
∑f
i
=100 ∑f
i
u
i
=15
We have,
A= 50, h= 20, N= 100 and ∑f
i
u
i
=15
∴Mean=A+h[
N
1
∑f
i
u
i
]
⇒Mean=50+20×
100
15
$$\Rightarrow Mean = 50+3= 53
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