A random sample of 175 items is drawn from a population whose standard deviation

Question

A random sample of 175 items is drawn from a population whose standard deviation is known to be sigma = 50. The sample mean is X = 920. (a) Construct an interval estimate for mu with 95 percent confidence. (Round your answers to 1 decimal place.) The 95% confidence interval is from to (b) Construct an interval estimate for mu with 95 percent confidence, assuming that sigma = 100. (Round your answers to 1 decimal place.) The 95% confidence interval is from to (c) Construct an interval estimate for mu with 95 percent confidence, assuming that sigma = 200. (Round your answers to 1 decimal place.) The 95% confidence interval is from to (d) Describe how the confidence interval changes as sigma increases. The interval stays the same as o increases. The interval gets wider as sigma increases. The interval gets narrower as sigma increases. The interval gets wider as sigma decreases.

Explanation / Answer

a) The statistical software output for this problem is:

One sample Z confidence interval:
: Mean of population
Standard deviation = 50

95% confidence interval results:

Hence,

The 95% confidence interval is from 912.6 to 927.4

b) The statistical software output for this problem is:

One sample Z confidence interval:
: Mean of population
Standard deviation = 100

95% confidence interval results:

Hence,

The 95% confidence interval is from 905.2 to 934.8

c) The statistical software output for this problem is:

One sample Z confidence interval:
: Mean of population
Standard deviation = 200

95% confidence interval results:

Hence,

The 95% confidence interval is from 890.4 to 949.6

d) Option B is correct.

Mean n Sample Mean Std. Err. L. Limit U. Limit 175 920 3.7796447 912.59203 927.40797

Related Questions

Navigate

• Browse (All)
• Browse A
• Subjects

---

---

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