The XYZ supermarket sells fresh milk supplied by a fresh milk company from Negeri Sembilan

The XYZ supermarket sells fresh milk supplied by a fresh milk company from Negeri Sembilan. Recently, a quality assurance check suggested that the amount of milk supplied is significantly different (less or more) from the quantity stated within the contract . 

As a Quality Assurance Officer, discuss on one of the points below and comment on at least two of your coursemates' posts:

1. In your own words, what does it mean by significantly different.
2. State the null and alternative hypothesis statements for this case study.
3. Do you suggest a one tail or two tail test?
4. Do you have any other suggestion(s) on handling this test?