algebra
posted by Anonymous .
The breaking strength (in pounds) of a certain new synthetic is normally distributed, with a mean of 165 and a variance of 9. The material is considered defective if the breaking strength is less than 156 pounds. What is the probability that a single, randomly selected piece of material will be defective? (Give the answer to two decimal places.)

Please only post your questions once. Repeating posts will not get a quicker response. In addition, it wastes our time looking over reposts that have already been answered in another post. Thank you.