# Worksheet practice for chapter 9.2

RHR/bpm
68
88
63
68
86
72
77
94
94
83
71
69
82
79
65

The human heart has a mean resting heart rate (RHR)of 72 beats per minute (bpm). The table gives the heart rates for students in ESS 101j Joggling class.

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
10. _________ Does the 95% confidence interval include the possibility of 72 bpm?
Confidence interval statistics
Statistic or ParameterSymbolEquationsOpenOffice
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