Studies show an XBox controlle.
Studies show an XBox controller has an average lifetime of 1,500 days. Assume the lifetimes are normally distributed with a standard deviation of 325 days.
1. Find the percentage of controllers that will fail during their first 895 days of use.
2. Find the percentage of controllers that will fail within 225 days of their average lifetime. (NOT the first 225 days!)
3. At what number of days should the lifetime warranty be set so that fewer than 3.5% of the controllers must be replaced under warranty?