9. Suppose that the unsupported stem diameters at the base of a particular species of sunflower plant have a normal distribution with an average diameter of 35 millimeter and a standard deviation of 3 millimeter. (a) What is the probability that a sunflower plant will have a basal diameter of more than 40 mm ? (b) What is the probability that a sunflower plant will have a basal diameter between 30 mm and 40 mm ? 10. The comprehensive strength of samples of cement can be modeled by a normal distribution with a mean of 6000 kilograms per square centimeter and a standard deviation of 100 kilograms per square centimeter. (a) What is the probability that a sample strength is less than 6250Kg/cm: ? (b) What is the probability that sample strength is between 5800 Kg/cms and 5900 Kg/cm- ? 11. The line width for semiconductor manufacturing is assumed to be normally distributed with a mean of 0.5 micrometer and a standard deviation of 0.05 micrometer. (a) What is the probability that a line width is greater that 0.62 micrometer ? (b) What is the probability that a line width is between 0.47 and 0.63 micrometer ? 12. The speed of a file transfer from a server on a campus to a personal computer at a student's college on a weekday evening is normally distributed with a mean of 60 kilobits per second and a standard deviation of 4 kilobits per second. (a) What is the probability that the file will transfer at a speed of 70 kilobits per second or more