8 and 9 please!

Incubation period for Covid-19 At the end of the pdf of this quiz (posted in the topic module) is a Wall Street Journal article about the incubation period of the coronavirus (how long it takes symptoms to appear after the person is exposed and contracts the virus). The article gives the median and a couple of probabilities. We'll make the additional assumption that the incubation period is approximately normally distributed in the population of people who contract the virus. There are 2 questions in this set. 8. Define X, to be the incubation period of Covid-19 in patient i. Assume that Xi has an approximately normal distribution with mean 5.1. (The article says the median is 5.1, and since we're assuming a normal distribution, which is symmetric, the mean also is 5.1). The article says that 0.975 of people develop symptoms within 11.5 days of exposure. In other words, P(Xi 14)? Four decimals COMMENT: The article says this probability is slightly more than 0.01. If your answer is different (which it will be!), this may mean the assumption of a normal distribution isn't quite right. Maybe the distribution isn't symmetric, or maybe the true distribution has "fatter tails" than the normal distribution