Question

The lifetime of a certain type of battery is normally distributed with mean value 12 hours and standard deviation 1 hour. there are four batteries in a package. what lifetime value is such that the total lifetime of all batteries in a package exceeds that value for only 5% of all packages? (round your answer to two decimal places.)

Answer 1

In most cases for this type of questions you would have to use a calculator, since this is not a value that can be approximated. Do you have an inverse normal function on your graphical calculator?