Topic 2: TI-83 Plus or TI-84 Plus Calculator Function

Given the following graphing calculator functions:

normalcdf(lower bound, upper bound, mean, standard deviation)

invNorm(area to the left, mean, standard deviation)

1. When would you use either of these functions?
2. If the average THC content of marijuana sold on the street is 10.5% and THC content is normally distributed with standard deviation of 2%. Which function would you use to (a) Find the probability that a randomly selected bag of marijuana sold on the street will have a THC content greater than 9.1, and (b) Find the 67th percentile for this distribution.