The engineering specifications provide that a gasket should be between 395 mm and 405 mm, otherwise a gasket is defective.Assuming the process is working correctly:

Mean is 400

SD is 2

1- find the probability that a randomly selected gasket is NOT defective.

We have that =400 and =2

z=x

P(395 < x < 405 ) = P( x < 405) - P(x < 395)

Use excel fuel = NORM.DIST(405,400, 2,TRUE) -NORM.DIST(395,400, 2,TRUE)

answer = 0.9876

2- find the probability that a randomly selected gasket IS defective.

-this is what I need help with, I have #1 complete, but I am confused on how to input #2.