If a is an m times ×n matrix whose columns do not span set of real numbers r superscript mℝm, then the equation axequals=b is consistent for every b in set of real numbers r superscript mℝm. choose the correct answer below.

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?