The average delivery time of electronic products from Singapore to the USA is 6 days. There are many corporate customers in the USA. Although an average of 6 days, at the customer side there has ever received the goods on day ten, but some are receive the item 4 days, two days faster than expected. There is also up to 21 days of goods not yet reached the hands of the customers.
For example, the service at fast food restaurants, the average time of presentation is 5 minutes. But there who have had the service up to 15 minutes food was not ready. There are also 3 minutes are ready, anyone ever get the service up to 25 minutes. Such example is the service time variation and, if averaged over 5 minutes.