The mean of five numbers is 30. If one number is excluded, their mean becomes 28. the excluded number is:

If \(\bar { x } \) represents the mean of n observations x₁, x₂, ..., x_n, then value of \(\sum_{i=1}^{n}\left(x_{i}-\bar{x}\right)\) is:

If each observation of the data is increased by 5, then their mean

Let \(\bar { x } \) be the mean of x₁, x₂, ..., x_n and y the mean of y₁, y₂, ..., y_n. If z is the mean of x₁, x₂, .... x_n, y₁, y₂, ..., y_n, then z is equal to

If \(\bar { x } \) is the mean of x₁, x₂, ..., x_n, then for a ≠ 0, the mean of ax₁, ax₂, ..., ax_n, \(\frac{x_1}{a}\), \(\frac{x_2}{a}\), ........, \(\frac{x_n}{a}\) is

If \(\bar { x_1 } \), \(\bar { x_2 } \), \(\bar { x_3 } \), ........, \(\bar { x_n }\) are the means of n groups with n₁, n₂, ....... n_n number of observations respectively, then the mean x of all the groups taken together is given by:

The median of the data
78, 56, 22, 34, 45, 54, 39, 68, 54, 84 is

For drawing a frequency polygon of a continous frequency distribution, we plot the points whose ordinates are the frequencies of the respective classes and abcissae are respectively:

Mode of the data
15, 14, 19, 20, 16, 15, 16, 14, 15, 18, 14, 19, 16, 17, 16 is

The mean of 25 observations is 26. Out of these observations if the mean of first 13 observations is 22 and that of the last 13 observations is 30, the 13th observation is: