In a recent study on the sleeping habits of adults, it was found that the average amount of sleep an adult gets each night is 7.2 hours. This figure has been consistent for many years. A new study aims to determine if the mean amount of sleep has decreased. For past studies the population standard deviation has been used as 1.5 hours. State the null and alternative hypotheses for the study on sleep duration. What is the test statistic fvor a smaple of 200 adults with a sample mean sleep duration of 6.9 hours