Answer:
If a box is supposed to contain 18 ounces, and the acceptable error is 1 ounce, then the acceptable range is:
18 oz - 1oz = 17oz to 18oz + 1oz = 19oz
Then the acceptable range is (17oz, 19oz)
if the weight is smaller than 17 oz, the box is not acceptable.
If the weight is bigger than 19 oz, the box is not acceptable.
Then the graph of the boxes that can not be sold as full boxes is:
<---16---------17-------18--------19-------20----------->
where 17oz and 19oz are not included, because are acceptable weigths.
