A random sample of 30 airline flights during a storm had a mean delay of 40 minutes. The standard deviation was 5 minutes, and the standard error of the mean is 0.9129. Calculate a 90% confidence interval for the average delay for all flights during a storm.
A) (38.2, 41.8)
B) (38.4, 41.6)
C) (31.5, 48.5)
D) None of the above

Question

Quizplus · Accepted Answer

The 90% confidence interval is calculated using the formula: mean ± (z-score * standard error). For 90% confidence, the z-score is approximately 1.645. Thus, the interval is 40 ± (1.645 * 0.9129) = (38.4, 41.6).

A Random Sample of 30 Airline Flights During a Storm