Step 1 :QUESTION 3: n = 45, \( \bar{x} = 659 \), \( \alpha = 0.05 \), Calculate \( \frac{s}{\sqrt{n}} \) for the confidence interval formula.
Step 2 :QUESTION 4: \( \mu = 12.5, \sigma = 2 \), Calculate \( z \) score for the bottom of the top \( 15\% \) and use \( x = \mu + (z \times \sigma) \) to find the length.
Step 3 :QUESTION 5: \( \mu = 50,000, \sigma = 1800, n = 50 \), Calculate \( z \) score for \( \bar{x} < 50,000 \) and use the standard normal table to find the probability.
Step 4 :QUESTION 6: \( \mu = 350, \sigma = 570 \), Calculate \( z \) score for your monthly cost and compare with the advertised mean.