An unbalanced scale with 7 blocks on the left side of the scale and 4 blocks on the right side of the scale for the image above, which action below allows the scale to be balanced? add 2 blocks to the left side. add 3 blocks to the right side. take away 3 blocks from the right side. take away 4 blocks from the left side.

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?