Question

The breaking strength (in pounds) of a certain new synthetic is normally distributed, with a mean of 125 and a variance of 25. The material is considered defective if the breaking strength is less than 115 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.)

Answer 1

\(\mu=125, \sigma=25 X=115 => Z=(X-\mu)/\sigma=(115-125)/25=-0.4\)
Using a normal distribution, look for the left tail for Z=-0.4.
If you textbook does not have a table, use:
https://www.stat.tamu.edu/~lzhou/stat302/standardnormaltable.pdf

Answer 2

thanks

Answer 3

Yw! :)