Question:
Find the mean of each of the following frequency distributions :
Solution:
Let the assumed mean be A = 25 and h = 10.
We know that mean, $\bar{X}=A+h\left(\frac{1}{N} \sum f_{i} u_{i}\right)$
Now, we have $N=\sum f_{i}=60, \sum f_{i} u_{i}=8, h=10$ and $A=25$.
Putting the values in the above formula, we have
$\bar{X}=A+h\left(\frac{1}{N} \sum f_{i} u_{i}\right)$
$=25+10\left(\frac{1}{60} \times(8)\right)$
$=25+\frac{80}{60}$
$=25+1.333$
$=26.333$
Hence, the mean is 26.333.
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