Normal distribution

Question

A worn, poorly set-up machine is observed to produce components whose length X follows a normal distribution with a mean equal to 14 centimeters and a variance equal to 9. Determine the probability that a component is at least 12 centimeters long._

Answer 1

p(x>/=12) n(14,9)

z= (12-14)/9=-2/9= -.222...

use z tables

p(x>-.22222) = about 58.793%