Explain wrong one please

4. [0.86/1 Points] DETAILS PREVIOUS ANSWERS DEVORESTAT9 3.6.085. MY NOTES ASK YOUR TEACHER PRACTICE ANOTHER Suppose small aircraft arrive at a certain airport according to a Poisson process with rate a = 8 per hour, so that the number of arrivals during a time period of t hours is a Poisson rv with parameter u - 8t. (Round your answers to three decimal places.) (a) What is the probability that exactly 6 small aircraft arrive during a 1-hour period? 0.122 What is the probability that at least 6 small aircraft arrive during a 1-hour period? 0.809 What is the probability that at least 12 small aircraft arrive during a 1-hour period? 0. 112 (b) What is the expected value and standard deviation of the number of small aircraft that arrive during a 90-min period? + expected value N standard deviation 3.464 (c) What is the probability that at least 28 small aircraft arrive during a 2.5-hour period? 0. 112 X What is the probability that at most 11 small aircraft arrive during a 2.5-hour period? 0.021 You may need to use the appropriate table in the Appendix of Tables to answer this