Please solve these for me

The square pyramid has a volume of 441 cubic inches. what is the value of x? 1/7x is the height x is the base

Olga bought a new skirt that cost $20. sales tax is 5%. how much did olga pay, including sales tax? 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?