The difference in gallons per day used is 3.6.
The formula to calculate a z-score is:

,
where X is the value used to calculate the score, μ is the mean and σ is the standard deviation. We have the z-scores so we must work backward:

For both equations, we will cancel the 1.2 by multiplying both sides:

Now we will cancel 2.2 from both equations by adding it to both sides:
3.6+2.2=X-2.2+2.2 and 0+2.2=X-2.2+2.2
5.8=X and 2.2=X
The difference in gas used per day would be given by
5.8-2.2 = 3.6.
Step-by-step explanation:
8 is more than 2/4 because the answer of 2/4 is 0.5 so 8 is more than 2/4
15 since its in the middle of 10 and 20
The equation of the linear regression is 
<h3>Graphing tool</h3>
To determine the line of best fit, we make use of a graphing tool
See attachment for the graph of the line of best fit
<h3>The equation</h3>
From the graphing tool, we have the following calculation summary
-
Sum of X = 440
- Sum of Y = 3601.5
- Mean X = 44
- Mean Y = 360.15
- Sum of squares (SSX) = 1440
- Sum of products (SP) = 5157
The regression Equation is then represented as:

Where:
and 

Also, we have:


So, the linear regression equation is:

Read more about linear regression at:
brainly.com/question/17844286
Three hundread and forty-seven million three hundread and sixteen thousand and twenty-nine....347,316,029