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In each of Exercises 8.63-8.68, we provide a sample mean, sample size, population standard deviation, and confidence level In each case, perform the following tasks:

a. Use the one-mean z-interval procedure to find a confidence interval for the mean of the population from which the sample was drawn.

b. Obtain the margin of error by taking half the length of the confidence interval.

c. Obtain the margin of error by using Formula 8.l on page 325

x¯=50,n=16,σ=5, confidence level =99%

Short Answer

Expert verified

Part (a) The 99%confidence interval for μis (46.781,53.219)

Part (b) The margin of error by using the half-length of the confidence interval is 3.219

Part (c) The margin of error by using the formula is 3.219

Step by step solution

01

Part (a) Step 1: Given information

x¯=50,n=16,σ=5, confidence level =99%

02

Part (a) Step 2: Concept

The formula used: the confidence interval x¯±zα2σnandMargin oferror(E)=za2σn

03

Part (a) Step 3: Calculation

Compute the 99%confidence interval for μ

Consider x¯=50,n=16,σ=5, and confidence level is 99%

The needed value of za2 with a 99% confidence level is 2.575, according to "Table II Areas under the standard normal curve."

Thus, the confidence interval is,

x¯±zα2σn=50±2.575516=50±2.575(1.25)=50±3.219=(46.781,53.219)

Therefore, the 99% confidence interval for μ is (46.781,53.219)

04

Part (b) Step 1: Calculation

Using the half-length of the confidence interval, calculate the margin of error.

Margin of error=Upper limit-Lower limit2=53.219-46.7812=6.4382=3.219

Thus, the margin of error by using the half-length of the confidence interval is 3.219

05

Part (c) Step 1: Calculation

Using a formula, calculate the margin of error.

Marginof error(E)=za2σn=2.575516=2.575(1.25)=3.219

Thus, the margin of error by using formula is 3.219

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