Q28 of 46 Page 278

The standard deviation of the data 6, 5, 9, 13, 12, 8, 10 is

Given data in tabular form can be written as

But we know, standard deviation can be written as

Substituting the corresponding values, we get

Hence the standard deviation of the data 6, 5, 9, 13, 12, 8, 10 is .

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

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:

Let x₁, x₂, ..., x_n be n observations and be their arithmetic mean. The formula for the standard deviation is given by

The mean of 100 observations is 50 and their standard deviation is 5. The sum of all squares of all the observations is