3. A phone manufacturer is testing the lifetime, in minutes, of its new phone's battery under heavy usage. The results are below, in minutes. Assume the distribution of battery life is normally distributed. 415 380 365 400 360 350 370 a) Find a point estimate for the population mean battery life under heavy usage. b) If we want to build a 95% confidence interval for the population mean battery life, what critical value will we use? c) Find the margin of error for a 95% confidence interval. d) Construct the 95% confidence interval. e) Can they conclude the battery life exceeds 6 hours? Why or why not