The mean life of a certain computer hard disk in continual use is 8 years. (a) How long a warranty should be offered if the vendor wants to ensure that not more than 10 percent of the hard disks will fail within the warranty period? (Round your answer to 4 decimal places.) Period of warranty years (b) How long a warranty should be offered if the vendor wants to ensure that not more than 20 percent of the hard disks will fail within the warranty period? (Round your answer to 4 decimal places.) Period of warranty years