Rejection with mean and standard dev given

#1
So I am having a little brain fart. The problem reads,

The snack pack of potato chips is advertised to weigh 3.5oz . The weights are normally distributed with a mean of 3.5oz. And a standard deviation of.2 oz. an inspector rejects packs that weigh less than 3 oz and more than 4 oz. what is the probability that a randomly selected pack will be rejected?

This is off of a test. I got it wrong and the teacher never went over how to get the right answer just showed us what it was. Help please!! Thank you for your time.
 

hlsmith

Less is more. Stay pure. Stay poor.
#2
Well the values are either 0.5 below or 0.5 above the mean, then you convert those into a standard deviation values (0.5/2), so -.25 sd below or above the mean, so what area for the standard normal curve is -0.25 sd below and 0.25 above, now sum those values and I would guess that is the solution.