For the right tail, is it appropriate to just calculate a mean and standard deviation, add 1, 2 & 3 standard deviations from the mean to create a range then compare that to the normal 68/95/99.7 for the standard normal distribution after using the norm.dist function in excel to test each standard deviation value.
The contagious period for a cold lasts about three to four days into the illness. As a general rule, people with a cold are most contagious about three days after their initial exposure to the virus. For more information on colds, influenza and related topics, check out the links on the next page.
How Long is a Cold Contagious? Colds are most contagious 2 to 4 days after your symptoms first develop. However, the virus can live in your body and spread to others for up to three weeks. That's right, you could spread your cold virus germs even after you feel better. Most cold last for about a week but it's possible to spread the virus long after that.