A random sample of 21 items is drawn from a population whose standard deviation

Question

A random sample of 21 items is drawn from a population whose standard deviation is unknown. The sample mean is x^- = 910 and the sample standard donation is s = 20 Use Appendix D to find the values of Student's t. (a) Construct an interval estimate of mu with 99% confidence. (Round your answers to 3 decimal places.) The 99% confidence interval is from to (b) Construct an interval estimate of mu with 99% confidence, assuming that s = 40.(round your answers to 3 decimal places.) The 99% confidence interval is from to (c) Construct an interval estimate of mu with 99% confidence, assuming that s = 80.(Round your answers to 3 decimal places.) The 99% confidence interval is from to (d) Describe how the confidence interval changes as s increases. The interval stays the same as s increases. The interval gets wider as s increases. The interval gets narrower as s increases.

Explanation / Answer

a) Critical value at 99% Interval and degree of freedom = 21-1 = 20 is 2.84534

99% Interval

(910-2.84534*20/Sqrt21), 91+2.84534*20/Sqrt(21))

=( 897.582, 922.418)

b) 99% Interval

(910-2.84534*40/Sqrt21), 91+2.84534*40/Sqrt(21))

=( 885.164, 934.836)

c) 99% Interval

(910-2.84534*80/Sqrt21), 91+2.84534*80/Sqrt(21))

=( 860.328, 959.672)

d) Option D is correct

Related Questions

Navigate

• Browse (All)
• Browse A
• Subjects

---

---

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