Final answer:
To construct a 90% confidence interval for the population mean time to complete a customer's tax forms, use the formula CI = X ± Z * (σ/√n) and substitute the given values.
Step-by-step explanation:
To construct a 90% confidence interval for the population mean time to complete a customer's tax forms, we can use the formula:
CI = X ± Z * (σ/√n)
where X is the sample mean, Z is the z-score corresponding to the desired confidence level (in this case 90%), σ is the population standard deviation, and n is the sample size. Since we know σ = 700, X = 23.6, and n = 100, we can substitute these values into the formula to calculate the confidence interval as:
CI = 23.6 ± 1.645 * (700/√100) = 23.6 ± 1.645 * 70 = 23.6 ± 115.15
Hence, the 90% confidence interval for the population mean time to complete a customer's tax forms is (22.228, 24.972).