algebra
posted by apryl .
The breaking strength (in pounds) of a certain new synthetic is normally distributed, with a mean of 167 and a variance of 9. The material is considered defective if the breaking strength is less than 161 pounds. What is the probability that a single, randomly selected piece of material will be defective? (Give the answer to two decimal places.)

Z = (scoremean)/SD
Variance = SD^2
Use the same table.