Question

The length of an instant message conversation is normally distributed with a mean of 5 minutes and a standard deviation of 0.7 minutes.

What is the probability that a conversation lasts longer than 6 minutes?

Answer 1

One way to answer this question would be to find the "z-score" for the value "6 minutes." Can you do that, using the given mean and standard deviation and letting x=6 minutes?

Now (for example ONLY): supposing the resulting z score were 1.1. What would be the area under the probability curve to the right of z=1.1? You could find this area using a TI calculator, or, if you don't have such a calculator, by using a table of z-scores.

What part of this discussion is familiar to you, and what part is not?