What is the bolume of a cone in terms of its base radius r

What numbers are included in the set of integers? what numbers are not included?

Can somebody 1. what is the formula for finding the vertical distance between two points on a coordinate plane?

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?