IDNLearn.com: Your trusted source for finding accurate answers. Discover the information you need from our experienced professionals who provide accurate and reliable answers to all your questions.

19. The average yearly income for 28 married couples living
in city C is $58,219. The standard deviation of the sample is
$56. Find the 95% confidence interval of the true mean.
20. The number of unhealthy days based on the AQI


Sagot :

Answer:

[tex]\{58198.2573,58239.7427\}[/tex]

Step-by-step explanation:

We assume that the following conditions are true before constructing the confidence interval:

Assumption #1: Random Sampling.

Assumption #2: Independence.

Assumption #3: Large Sample.

Assumption #4: The 10% Condition (sample size is no bigger than 10% of population

Assumption #5: The Success / Failure Condition.

Assumption #6: Homogeneity of Variances.

A 95% confidence level correlates to a critical value of [tex]z^*=1.96[/tex], hence:

[tex]\displaystyle CI=\bar{x}\pm z^*\biggr(\frac{s}{\sqrt{n}}\biggr)\\\\CI=58219\pm 1.96\biggr(\frac{56}{\sqrt{28}}\biggr)\\\\CI=58219\pm20.7427\\\\CI=\{58198.2573,58239.7427\}[/tex]

Therefore, we are 95% confident that the true mean of the average yearly income for a married couple living in city C is between $58,198.2573 and $58,239.7427