The times required for a cable company to fix cable problems

The times required for a cable company to fix cable problems are normally distributed with a mean of 18 minutes and a standard deviation of 3.5 minutes. 1. What is the probability that a randomly selected cable repair visit will take at least 20 minutes?

Solution

We use exce function 1-normdist(20,18,3.5,1) = 0.2839