Small boxes of NutraFlakes cereal are labeled "net weight 10 ounces." Each hour, a random sample of 6 boxes is weighed to check process control. Five hours of observations yielded the following sample information. Construct a 3-sigma R chart. What does the chart tell you? Hour 1 2 3 4 5 Sample mean (x-bar) 10.5 10.0 9.6 10.5 9.4 ∑x-bar =50.0 Sample range (R) 0.8 1.2 0.9 0.6 0.5 ∑R =4.0

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?