Case 1: To get the confidence interval for each variable for three Confidence Levels (90%, 95%, and 99%)
I used formula
𝑥 ± Z 𝑠
√𝑁
Income:
Sample Size: 174
Sample Mean: 52300.54
Standard Deviation: 15971.60
Confidence Level: 90%
52300.54 ± 1.645 x 15971.60
√174 = 52300 ± 1990
With 90% confidence the population mean is between 50300 and 54300, based on 174 samples.
Confidence Level: 95%
52300.54 ± 1.960 x 15971.60
√174 = 52300.54 ± 2370
