The mean deviation about median from the data 340, 150, 210, 240, 300, 310, 320, is

Arranging the observations in ascending order of magnitude, we have 150, 210, 240, 300, 310, 320, 340. Clearly, the middle observation is 300.

$∴$ Median= 300.

Calculation of Mean Deviation

x i

|d_{i}| = |x_{i} - 300|

340

150

210

240

300

310

320

150

Total

d_{i} = 2 \frac{1}{4} |x_{i} - 300| = 370

$∴ M . D . = \frac{1}{n} Σ |d_{i}| = \frac{1}{7} Σ |x_{i} - 300| = \frac{370}{7} = 52.8$

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