The length of a text messaging conversation is normally distributed with a mean of 2 minutes and a standard deviation of .5 minutes. what is the probability that a conversation lasts longer than 3 minutes? ,

This would be a bell curve with a z-score of greater than +2.00, since 3 minutes is exactly two standard deviations greater than the mean of 2.00. Looking at a z-score table for the proportion of the curve that lies in the 1-tailed area greater than 2.00, we find that the value is .0228. This would be the probability that the conversation is over three minutes: 0.0228 or 2.28%.