mean = 165
defective if <156.2
variance = 16
so sigma = sqrt 16 = 4 (did you notice that?)
then use Davidlane
The breaking strength (in pounds) of a certain new synthetic is normally distributed, with a mean of 165 and a variance of 16. The material is considered defective if the breaking strength is less than 156.2 pounds. What is the probability that a single, randomly selected piece of material will be defective? (You may need to use the standard normal distribution table. Round your answer to four decimal places.)
My teacher assigned this problem online. I've tried finding this answer by plugging the numbers into the formula and using the standard normal distribution table, but I'm not coming up with the right number. This is the last problem on my last homework assignment before the semester ends. Please help me!
2 answers
mean = 165
defective if <156.2
variance = 16
so sigma = sqrt 16 = 4 (did you notice that?)
then use Davidlane
http://davidmlane.com/hyperstat/z_table.html
I get 0.0139
or 1.39 percent
defective if <156.2
variance = 16
so sigma = sqrt 16 = 4 (did you notice that?)
then use Davidlane
http://davidmlane.com/hyperstat/z_table.html
I get 0.0139
or 1.39 percent