Find the critical value t for the following situations. a) a 98% confidence interval based on df = 10. b) a 99% confidence interval based on df = 81. Click the icon to view the t-table. a) What is the critical value of t for a 98% confidence interval with df = 10? (Round to two decimal places as needed.) b) What is the critical value of t for a 99% confidence interval with df = 81? (Round to two decimal places as needed.)