Confidence intervals using mean

Hi- I'm very confused on this question- any help would be great!

Consumer reports randomly tested 14 brands of vanilla yogurt and found the following numbers of calories per serving:

160,200,220,230,120,180,140,130,170,190,80,120,100,170

a) Create a 95% confidence interval for the mean calorie content of vanilla yogurt
b) A diet guide claims that ou will get 120 calories for a serving of vanilla yogurt. WHat do the baove data indicate? Test an appropriate hypothesis and state your conclusion.

I am totally confused on what to do using the mean. do I use SE=(squareroot (pq/n) and if so how do I know what p is equal to?

Thanks a lot!!

You are measuring a quantity directly, not a proportion. 'p' is not the plan.

Try the mean and standard deviation.

Ok I understand that you need to use the formula SE(ybar)= s/squareroot (n)

ybar= 158 calories

How do you figure out what s is equal to?

I'm not encouraged.

You should have formulas for the standard deviation of a sample. Is it not in your book? Do you have one?

Do you have a fancy calculator? Such a thing will just do it for you, but I recommend doing it yourself first, at least once in your life.