A GRE prep company advertises that average score improvement in GRE scores of their students is equal to 50 points. A consumer group believes this is incorrect and randomly samples 31 students who have taken the GRE prep course from this company. They find that the sample has an average improvement of 39 points with a standard deviation of 37 points. Evaluate the consumer groups belief that the company's advertised score improvement is incorrect. Use a 5% level of significance. What is the hypothesis? p-value?