One sample t test for mean.

National Packing Materials Company claims its X20 box can hold loads up to at least 80 pounds. Smith Widget Company has been using the boxes for one year and feels the boxes fail at lighter loads. Hearing the complaints from Smith, the lead engineer for National Packaging decides to test the company’s claim that it can hold at least 80 pounds. He decides to text 64 boxes at the .05 level of significance. He finds a meanof 78 pounds with a standard deviationof 5 pounds. What is the critical value for this test? What is the value of the test statistic? What is the Null hypothesis? What is the alternate hypothesis? What is the standard errorof the mean? Should the Null hypothesis be accepted or rejected?

A step-by-step method for testing the hypothesis under 5 step approach is discussed here (see attachment).