I need help with this quiz please help is in mastery connect. the code is 100958 if you need a student code this is 0615136449 if this code don't work try with this P09/10/2007 help please

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Me n o w. i need t h i s. 10 points

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?