On december 18, 2009, cesar cielo filho of brazil set a world record by swimming 50 m on a long course (50-m pool) in 20.91 sec. this record is 0.61 sec longer than the record on the 50-m short course (25-m pool), which was set by roland schoeman of south africa on august 8, 2009. by what percent is the record for a short course faster than the record for a long course

Assume that there is a 11% rate of disk drive failure in a year. a. if all your computer data is stored on a hard disk drive with a copy stored on a second hard disk drive, what is the probability that during a year, you can avoid catastrophe with at least one working drive? b. if copies of all your computer data are stored on four independent hard disk drives, what is the probability that during a year, you can avoid catastrophe with at least one working drive?