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Problem :

x = 0-4 , 4-10 , 10-18 , 18-30 , 30-40

f(x) = 15 , 35 , 20 , 20 , 10

Finding the median?

This is that I did :

Cumulative frequency distribution :

F(x) = 15 , 50 , 70 , 90 , 100

Midpoint : 2 , 7 , 14 , 24 , 35

Formula : $Md = L_0 + \frac{\frac{n}{2}-F(x_{m-1})}{f(x_m)}*(L_1-L_0)$

n=100, $$\frac{100}{2} = 50$$

But F(x) = 50? I don't understand how to continue?

Thanks.

JaVaPG
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    It should be obvious that the median should be near $10$. Consider what proportion of the values (at least) are $10$ or below, and what proportion $10$ or above. – Henry Jul 23 '14 at 22:54

1 Answers1

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$L_0$ is the lower limit of interval, where the median is inside.

$\frac{n}{2}=50 \ \ \color{blue} \checkmark$

$F(x_{m-1})$ is the cumulative frequency below the interval of the median. It is 15

$f_{xm}$=freqency in the Intervall of the median. It is 35

$L_1$ is the upper limit of interval, where the median is inside.

$=4+\frac{50-15}{35}\cdot (10-4)=4+6$

callculus42
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