Question

Sales volume last weekend for a sample of ten car dealerships were as follows:

Data Point	1	2	3	4	5	6	7	8	9	10
# Sales	21	10	19	35	23	34	44	29	15	30

What is the variance of the sample data?

Please round your answer to the nearest tenth.

Note that the correct answer will be evaluated based on the full-precision result you would obtain using Excel.

Answer 1

Solution :

We have a sample of size n = 10 .

To find the variance of this sample , we construct a table using Excel.

	x	x2
	21	441
	10	100
	19	361
	35	1225
	23	529
	34	1156
	44	1936
	29	841
	15	225
	30	900
SUM	260	7714

Sample variance s² =

= [1/(10 - 1)][7714 - (260²/10) ]

= 106.0

The variance of the given sample data is 106.0

{

We can directly find the sample variance in excel. Use function

= VAR(select data)

}

The variance of the given sample data is 106.0