Assuming .05 as your alpha value, make up a problem similar to this one. Make up 36 gas prices for your example. Use price values in your list that some you made up and be sure they are similar to the prices you have had in your area. List the values in your post.

Instructions for your response. You will respond to at least 2 classmates.

In your response, copy the original problem, describe what you did and give the mean, standard deviation and confidence interval. Then attach the excel spreadsheet below so students and the professor can check your work.

Example below:

First find the mean. List all 36 gas prices in cells A1 to A36 in your excel spreadsheet.

On a different cell type in =average(A1:A36) and the hit enter to find the average

Assume your answer is 2.65

On a different cell type in =stdev.s(A1:A36) or =stdevA(A1:A36) and enter to find the standard deviation

Assume your answer is .43

Then type this in an excel cell =confidence.norm(.05,.43,36) and hit enter. This is the E value

So take the mean of 2.65 and you have (2.65-E, 2.65+E) for your confidence interval

Formula you used above for the confidence interval:

The formula is E= zsubc * sigma / sqrt n

Where the left hand endpoint is xbar – E and the right hand endpoint is xbar + E

Just a review of your instructions:

First you will make up a problem with alpha = .05 and give the values for the problem. This is your main post.

Then will make 2 responses copying the problem, explaining all work and giving the solutions to 2 classmates problems. On each you will attach your excel spreadsheet showing your work. Pick 2 students who do not have responses if possible.

**MODEL ANSWER**

Alpha value is .05

As depicted in the attached excel file, I started by listing the gas prices from A1 to A36.

Data:

$1.65 $1.78 $1.88 $1.89 $1.99 $2.00 $2.02 $2.04 $2.21 $2.22 $2.23 $2.27 $2.31 $2.34 $2.42 $2.43 $2.44 $2.50 $2.51 $2.52 $2.53 $2.55 $2.56 $2.57 $2.58 $2.71 $2.75 $2.85 $2.87 $2.89 $2.99 $3.02 $3.09 $3.12 $3.11 $2.24

The mean/average is calculated by entering =average(A1:A36) in a different cell. The answer is 2.45

The xxxx is computed by entering =stdevA(A1:A36) in a xxx cell. The answer is equal to 0.39

To get the xxx of E, typed = xxx.norm(.05,.39,36) and obtained 0.13

With a xxx of 2.45, the xxx is computed as xxx:

(2.45 – E, 2.45 + E) = (2.45 – 0.13, 2.45 + 0.13) = (2.32, 2.57)