Question

Paki surveyed the price of unleaded gasoline (self-serve) at gas stations in Novato and Lafayette. The raw data, in dollars per gallon, are given in the following table.

Novato	2.899	3.089	3.429	2.959	2.999	3.099
Lafayette	3.589	3.389	3.189	3.189	3.559	3.349

Find the standard deviation of prices in each city. (Round your answers to three decimal places.)

Novato	$
Lafayette	$

Which city has more consistently priced gasoline? Why?

The gas in Lafayette is more consistently priced because it has a smaller mean.The gas in Lafayette is more consistently priced because it has a smaller standard deviation.    The gas in Novato is more consistently priced because it has a smaller standard deviation.The gas in Novato is more consistently priced because it has a smaller mean.

Answer 1

For Novato

Create the following table.

data	data-mean	(data - mean)2
2.899	-0.18	0.0324
3.089	0.01	0.0000
3.429	0.35	0.1225
2.959	-0.12	0.0144
2.999	-0.08	0.0064
3.099	0.02	0.0004

Find the sum of numbers in the last column to get.

So standard deviation is

Now for Lafayette

Create the following table.

data	data-mean	(data - mean)2
3.589	0.2117	0.04481689
3.389	0.0117	0.00013689
3.189	-0.1883	0.03545689
3.189	-0.1883	0.03545689
3.559	0.1817	0.03301489
3.349	-0.0283	0.00080089

Find the sum of numbers in the last column to get.

So

Lower the standard deviation, more consistent the data

Hence answer here is The gas in Lafayette is more consistently priced because it has a smaller standard deviation.