Not getting Type II error at all. I keep getting that the type II error is essentially 0, making the power 1. That can't be right.
Question:
Batteries need to be recharged every 4 hours. A sample of 50 is taken and they last 4.05 hours. The battery life is normally distributed with STD=0.2 hours. With alpha=.05, can one adopt the alternative hypothesis that batteries have over 4 hours of life. If the true battery life is 4.5, calculate the Power of the test. Also, what sample size would be required to detect a true mean battery life of 4.5 hours if we wanted the power of the test to be at least 0.9 ?