Ex:           An engineer measures the following beta values for bipolar transistors with the aim of finding nominal values of gain, (i.e., beta), to list on a datasheet.

        β1 = 111      β2 = 136      β3 = 159      β4 = 141      β5 = 109      β6 = 121

        β7 = 117      β8 = 105      β9 = 99        β10 = 102

Find the sample mean of the data.

Sol'n:      The sample mean is the average of the data values:

Here, n = 10 is the number of data points, and the Xi are the β values. Using a spreadsheet to sum the β values and divide by 10, we have our sample mean:

sample mean