Final answer:
To construct a confidence interval, the necessary information required includes the sample mean, standard deviation, sample size, and the desired level of confidence.
Step-by-step explanation:
To construct a confidence interval, we need to know the sample mean, standard deviation, sample size, and the desired level of confidence. Unfortunately, the given question only mentions the number of unhealthy days based on the AQI in a random sample of metropolitan areas without providing the necessary information to calculate a confidence interval. However, if you were provided with the necessary data, you could use the formula:
Confidence Interval = sample mean ± (Critical value) × (Standard deviation / √(sample size))
Where the critical value is determined based on the desired level of confidence and sample size.