the average battery life of the iPhone is reported to be 6.0 hours by Apple. Assume that the standard deviation for the battery life for this cell phone is 30 minutes. A random sample of 50 iPhones was found to have an average battery life of 5.7 hours. Use a 90% confidence interval to test whether Apple's claim is validated by 90% confidence interval. You need to answer two things: 1. Whether claim is valid? 2. Reason why it is valid or not valid.