Chapter 5.2, Problem 7E

Finding Probabilities for Normal Distributions In Exercises 7–12, find the indicated probabilities. If convenient, use technology to find the probabilities.

7. World Happiness In a recent study on world happiness, participants were asked to evaluate their current lives on a scale from 0 to 10, where 0 represents the worst possible life and 10 represents the best possible life. The responses were normally distributed, with a mean of 5.4 and a standard deviation of 2.2. Find the probability that a randomly selected study participant’s response was (a) less than 4. (b) between 4 and 6. and (c) more than 8. Identify any unusual events in parts (a)–(c). Explain your reasoning. (Source: The Earth Institute. Columbia University)