help with this. Last 2 are wrong. Thanks!

It is estimated that 11% of those taking the quantitative methods portion of the certified public accountant (CPA) examination fail that section. Sixty five students are taking the examination this Saturday. a-1. How many would you expect to fail? (Round the final answer to 2 decimal places.) Number of students 7.15 a-2. What is the standard deviation? (Round the final answer to 2 decimal places.) Standard deviation 2.52 b. What is the probability that exactly three students will fail? (Round the final answer to 4 decimal places.) Probability 0.0432 c. What is the probability at least three students will fail? (Round the final answer to 4 decimal places.) Probability 0.9791