A Real Estate company in Santa Fe (Mexico City), in January 2020, offers a promotional package for its products: 

The chamber of commerce wants to have the estimate of the average monthly cost of a low-cost 3-bedroom house. A random sample of 40 houses available for rent revealed that the average monthly cost was $323, and the sample standard deviation was $25. It was estimated that the average monthly cost in dollars of this product, according to 80% confidence, is: