Pls help me in this question

Can't gugys answer the ratio question. this is urgent the plans of a building is drawn toward scale of 1: 1000. kfc the foyer on the plans measures 62mm by 54mm, how large is the foyer in real life?

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?

Solve the equation.then check your solution 8=1.88+a