I have two problems - one I can solve on the calculator but I do not know how to write it out properly . 1. Given a population with a normal distribution, a mean of 15, and a standard deviation of 2, what value has an area of 0.8 to the left? On calc its solved via invNorm (0.8, 15, 2, Left) for 16.6832 but how do I write it out?

Problem two I have no idea to write or solve. 2. Given the population with a normal distribution, a mean of 200, and a stand deviation of 15, which two values form the upper and lower boundary of the middle 80%?