When Sahara runs the 400 m dash, finishing times are normally distributed with a mean of 84 seconds in a standard deviation of 1.5 seconds using the empirical rule, what percentage of races while her finishing time be between 81: 87 seconds?

Dana wants to identify the favorite professional baseball team of people in her community. she stands outside a local sporting goods store and asks every other person who enters, "what is your favorite professional baseball team? " will the results of her survey be valid? explain.