What are the 3 dimensions referenced when we say 3D?

Lisa has a section of her document that she would like to include in the index. which option should lisa choose? mark index mark entry insert endnote add text

Assume that there is a 4% 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 three independent hard disk drives, what is the probability that during a year, you can avoid catastrophe with at least one working drive?

Which task uses a simple parameter?