In a random sample of 60 computers, the mean repair cost was $150. Assume the population standard deviation is $36. Construct a 90% confidence interval for the population mean.
A)($142, $158)
B)($138, $162)
C)($141, $159)
D)($537, $654)

Question

Quizplus · Accepted Answer

The 90% confidence interval for the population mean is calculated using the formula: mean ± Z*(σ/√n), where Z is the Z-score corresponding to the confidence level (for 90%, Z ≈ 1.645), σ is the population standard deviation, and n is the sample size. Plugging in the given values: 150 ± 1.645*(36/√60), we get approximately ($142, $158).

In a Random Sample of 60 Computers, the Mean Repair