### MS 150 Statistics q09 • Name:

The Journal of the American Medical Association published an article on 08 August 2001 that reported on vitamin A deficiency among children in the Federated States of Micronesia. The study found that a sample size n of 218 Yapese children had a mean blood serum level of retinol (vitamin A) x of 22.9 µg/dL with a sample standard deviation sx of 6.25 µg/dL.

1. __________ What level of measurement is the data?
2. __________ What is the sample size n for the data?
3. __________ What is the sample mean x?
4. __________ What is the point estimate for the population mean μ?
5. __________ What is the sample standard deviation sx?
6. __________ Calculate the sample coefficient of variation CV.
7. ____________________ Calculate the standard error of the sample mean x.
8. ____________________ Calculate the value of tcritical
9. ____________________ Calculate the margin of error E for the sample mean x.
10. Calculate the 95% confidence interval for the population mean serum retinol level for the Yapese children.

p(__________ < μ <__________) = 0.95
11. ____________________ The population mean serum retinol level for children in the United States μ is 35 µg/dL. Is 35 a possible population mean value for the Yapese children?
12. ____________________ Is the serum retinol (vitamin A) level for children in Yap statistically significantly different from that for children in the United States?

According to reseach done by Eelmine Järgmine the inline style attribute is used on a proportion p equals 61.51% of all web pages. Consider a sample of n equals 100 pages.

1. __________ What is the point estimate for the population proportion P?
2. ____________________ Calculate the standard error of the sample proportion p.
3. ____________________ Calculate the value of tcritical
4. ____________________ Calculate the margin of error E for the sample proportion p.
5. Calculate the 95% confidence interval for the population proportion usage of the style attribute.

p(__________ < P <__________) = 0.95
Confidence interval statistics
Statistic or ParameterSymbolEquationsOpenOffice
Sample sizenn=COUNT(data)
Degrees of freedomdfn − 1=COUNT(data)-1
Find a tcritical value from a confidence level c tc =TINV(1-c;df)
Standard error of a sample mean x SE =STDEV(data)/SQRT(n)
Standard error of a sample proportion p SE =SQRT(p*q/n)
Calculate a margin of error for the mean E using tcritical and the standard error SE. E =tc*SE
Calculate a confidence interval for a population mean μ from a sample mean x and a margin of error E x - E < μ < x + E
Calculate a confidence interval for a population proportion P from a sample proportion p and a margin of error E p - E < P < p + E