Please help with A to C , thanks

Question 3, 9.3.20-E ) HW Score: 7.94%, 0.56 of 7 points PartZ of6 0 Points: 0 of 1 Homework: Chapter 9 Homework In 2017, the average credit score for loans that were purchased by a government-sponsored mortgage loan company was 743. A random sample of 35 mortgages recently purchased by the company was selected, and it was found that the average credit score was 753 with a sample standard deviation of 21. Complete pans a through c. a. Using 0: =0.05, is there enough evidence from this sample to conclude that the average credit score for mortgages purchased by the company has increased since 2017? Determine the null and alternative hypotheses. H0: u s 743 H1: u > 743 (Type integers or decimals. Do not round.) Determine the appropriate critical value. Select the correct choice below and fill in the answer box within your choice. (Round to three decimal places as needed.) OA' \"u/2:1