How many significant figures in 3400?

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?

If the probability of an event happening is 65% then the probability this event does not occur?

You use technology ans find a sum of 6.712e-8. write this sum in standard form