A doctor wants to estimate the HDL cholesterol of all 20-to 29-year-old females.

Question

A doctor wants to estimate the HDL cholesterol of all 20-to 29-year-old females. How many subjects are needed to estimate the HDL cholesterol within 2 points with 99% confidence assuming sigma = 13 1? Suppose the doctor would be content with 95% confidence. How does the decrease in confidence affect the sample size required? A 99% confidence level requires _ subjects. (Round up to the nearest whole number as needed) A 95% confidence level requires _ subjects. (Round up to the nearest whole number as needed.) How does the decrease in confidence affect the sample size required? A. The lower the confidence level the smaller the sample size. B. The sample size is the same for all levels of confidence C. The lower the confidence level the larger the sample size.

Explanation / Answer

For 99% CI, z-critical value = 2.58

Margin of error = z*sigma/sqrt(n)

2 = 2.58*13.1/sqrt(n)

n = (2.58*13.1/2)^2 = 285.58 = 286 (approx)

For 95% CI, z-critical value = 1.96

Margin of error = z*sigma/sqrt(n)

2 = 1.96*13.1/sqrt(n)

n = (1.96*13.1/2)^2 = 164.81 = 165 (approx)

As we observed from above calculations, The lower the confidence level the smaller the sample size.

Related Questions

Navigate

• Browse (All)
• Browse A
• Subjects

---

---

Integrity-first tutoring: explanations and feedback only — we do not complete graded work. Learn more.