Accrotime is a manufacturer of quartz crystal watches. Accrotime researchers have shown that watches have an average life of 29 months before certain electronic components deteriorate, causing the watch to become unreliable. The standard deviation of watch lifetimes is 5 months, and distribution of lifetimes is normal.
(a) If Accrotime guarantees a full refund upon any defective watch for 2 years after purchase, what percentage of total production will company expect to replace? (Round your answer to two decimal places.)
answer is a %
(b) If Accrotime doesn't want to make refunds upon more than 8% of the watches it makes, how long should guarantee period be (to the nearest month)?