| Class : | 10-20 | 20-30 | 30-40 | 40-50 | 50-60 |
|---|---|---|---|---|---|
| Frequency : | 110 | 54 | 30 |
If the sum of all frequencies is 584 and median is 45, then | | is equal to .
View written solutionFree
Correct answer: 164
- Given frequency table
[ \begin{array}{c|ccccc} \text{Class} & 10-20 & 20-30 & 30-40 & 40-50 & 50-60 \ \hline \text{Frequency} & \alpha & 110 & 54 & 30 & \beta \end{array} ]
Total frequency is given as [ \alpha+110+54+30+\beta=584 ] so [ \alpha+\beta+194=584 ] [ \alpha+\beta=390 \qquad ...(1) ]
- Use the median formula
Total number of observations: [ N=584 ] Hence, [ \frac{N}{2}=292 ]
Given median is .
The median class is clearly , because median value lies in this class.
For grouped data, [ \text{Median}=l+\left(\frac{\frac{N}{2}-c_f}{f}\right)h ] where:
- (lower limit of median class),
- ,
- (frequency of median class),
- .
Substitute in the formula: [ 45=40+\left(\frac{292-(\alpha+164)}{30}\right)10 ]
Simplify: [ 5=\left(\frac{128-\alpha}{30}\right)10 ] [ 5=\frac{128-\alpha}{3} ] [ 15=128-\alpha ] [ \alpha=113 ]
- Find using (1)
[ \alpha+\beta=390 ] [ 113+\beta=390 ] [ \beta=277 ]
- Compute
[ |\alpha-\beta|=|113-277|=164 ]
- Final Answer
[ \boxed{164} ]
The derived answer matches the stored correct answer.
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