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NCERT Class XI Mathematics - Statistics - Solutions

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Question : 5 of 34
Marks: +1, -0
xix_i5 10 15 20 25
fif_i 7 4 6 3 5
Solution:  
xix_i 5 10 15 20 25
fif_i 7 46 3 5 25
fixif_i x_i 35 4090 60 125 350
∣xi−14∣|x_i - 14|9 4 1 6 11
fi∣xi−14∣f_i |x_i - 14| 63 16 6 18 55158
Mean (x−)\left(\overset{-}{x}\right) = 1N∑i=1nfixi\frac{1}{N} \sum\limits_{i=1}^{n} f_i x_i = 125×350\frac{1}{25} \times 350 = 14
∴ Mean deviation about mean = 1N∑i=1nfi∣xi−x−∣\frac{1}{N} \sum\limits_{i=1}^{n} f_i \left|x_i - \overset{-}{x}\right| = 125\frac{1}{25} × 158 = 6.32
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