The absolute value of a complex number z = a + bi, denoted |z|, is given by the formula |z| = p a 2 + b 2 find six distinct complex numbers (which are neither purely imaginary nor purely real) such that each has an absolute value of 7

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?