Find the Probability and inverse probability for the given Normal distribution.
Accrotime is a manufacturer of quartz crystal watches. Accortime researchers have shown that the watches have an average life of 28 months before certain electronic components deteriorate, causing the watch to become unreliable. The standard deviation of watch lifetimes is 5 months, and the distribution of lifetimes is normal.
1) State the random variable.
2) If Accrotime guarantees a full refund on any defective watch for 2 years after purchase, what percentage of total production will the company expect to replace?
3) If Accrotime does not want to make refunds on more than 12 percent of the watches it makes, how long should the guarantee period be (to the nearest month)?