Answer:
The margin of error for the 95% confidence interval for the mean score of all such subjects is of 8.45.
Step-by-step explanation:
We have the standard deviation for the sample, which means that the t-distribution is used to solve this question.
The first step to solve this problem is finding how many degrees of freedom, we have. This is the sample size subtracted by 1. So
df = 27 - 1 = 26
95% confidence interval
Now, we have to find a value of T, which is found looking at the t table, with 26 degrees of freedom(y-axis) and a confidence level of 
. So we have T = 2.0518
The margin of error is:
In which s is the standard deviation of the sample and n is the size of the sample.
In this question:
. So
The margin of error for the 95% confidence interval for the mean score of all such subjects is of 8.45.
You would divide 245 by 49 to get a
a= 5
Peggy has 12 practice sessions
The first step is finding the unit rate. We can do this by evaluating
21/1.75 divided by 1.75/1.75.
When you divide the two, you get 12.
To check your work you do 12(1.75) and you will get 21
Step-by-step explanation: This simple confidence interval calculator uses a Z statistic and sample mean (M) to generate an interval estimate of a population mean (μ).
Note: You should only use this calculator if (a) your sample size is 30 or greater; and/or (b) you know the population standard deviation (σ), and use this instead of your sample's standard deviation (an unusual situation). If your data does not meet these requirements, consider using the t statistic to generate a confidence interval.
where:
M = sample mean
Z = Z statistic determined by confidence level
sM = standard error = √(s2/n)
As you can see, to perform this calculation you need to know your sample mean, the number of items in your sample, and your sample's standard deviation (or population's standard deviation if your sample size is smaller than 30). (If you need to calculate mean and standard deviation from a set of raw scores, you can do so using our descriptive statistics tools.)
