# MS 150 Statistics q08 9.2 • Name:

Index of refraction
2.25
1.60
1.38
1.41
1.27

The data gathered by scientist Etse during physical science laboratory ten on the index of refraction of water is reported in the table.

1. _________ Calculate the sample size n.
2. _________ Calculate the sample mean x.
3. _________ Calculate the sample standard deviation sx.
4. _________ What is the point estimate for the population mean μ?
5. _________ Calculate the standard error SE.
6. _________ Calculate the number of degrees of freedom.
7. _________ Calculate t-critical tc for a confidence level c of 95% (0.95)
8. _________ Calculate the margin of error E.
9. Calculate the 95% confidence interval for the population mean μ

p(__________ ≤ μ ≤ __________) = 0.95
Confidence interval statistics
Statistic or ParameterSymbolEquationsOpenOffice 3.0 on Ubuntu 9.04
Degrees of freedomdfn − 1 =COUNT(data)-1
Find a tcritical value from a confidence level c tc =TINV(1-c,df)
Standard error of the sample mean SE =STDEV(data)/SQRT(sample size n)
Calculate a margin of error for the mean E for n ≥ 5 using sx. E =tc*sx/SQRT(n)
Calculate a confidence interval for a population mean μ from a sample mean x and an error tolerance E x − E ≤ μ ≤ x + E