Question

Find the mean and standard deviation of the following data:

5, 6, 7, 8, 9

Based on these results, check whether the value of 10 unusual?

Answer 1

Following table shows the calculations;

	X	(X-mean)^2
	5	4
	6	1
	7	0
	8	1
	9	4
Total	35	10

Sample size: n=5

The mean is:

The standard deviation is:

The data values that are within 2 standard deviations of mean considered as usual data values. The usual range of values is:

Since 10 lies in the above range so it is not unusual.