Rachel loves to bake cookies, but she has an old oven that has trouble maintaining a constant temperature. Assume the acceptable temperature range for making the cookies is 350 plus or minus 9 degrees. Six Sigma quality (3.4 defects pe million units produced) is probably a bit much to ask of Rachel's old oven. a. What would the standard deviation in the temperature of her oven need to be if she settled for a "Three Sigma" leve of quality? b. If her oven exactly meets a "Three Sigma" quality level, what percentage of the time would her oven be operating at temperature outside the acceptable range? Use Table 6-5. Complete this question by entering your answers in the tabs below. If her oven exactly meets this quality level, what percentage of the time would her oven be operating at a temperature outside the acceptable range? Use Table 6-5. Note: Round your answer to 2 decimal places