Help pls​

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?

Plzzz answer both questions and i will give you 100 points

Lana's family entered a 5-kilometer race lana's average step length is about 0.5 meter how many steps will she need to take the finish