Q25 of 46 Page 278

Mean deviation for n observations x1, x2, ..., xn from their mean is given by

We know for n observations x1, x2, ..., xn having is given by


But we know


So mean deviation becomes,



Or


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While calculating the mean and variance of 10 readings, a student wrongly used the reading 52 for the correct reading 25. He obtained the mean and variance as 45 and 16 respectively. Find the correct mean and the variance.

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The mean deviation of the data 3, 10, 10, 4, 7, 10, 5 from the mean is

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When tested, the lives (in hours) of 5 bulbs were noted as follows:

1357, 1090, 1666, 1494, 1623


The mean deviations (in hours) from their mean is

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Following are the marks obtained by 9 students in a mathematics test:

50, 69, 20, 33, 53, 39, 40, 65, 59


The mean deviation from the median is: