Over 500 million tweets are sent per day (digital marketing ramblings website, december 15, 2014). assume that the number of tweets per hour follows a poisson distribution and that bob receives on average 7 tweets during his lunch hour. a. what is the probability that bob receives no tweets during his lunch hour (to 4 decimals)? b. what is the probability that bob receives at least 4 tweets during his lunch hour (to 4 decimals)? c. what is the expected number of tweets bob receives during the first 30 minutes of his lunch hour (to 1 decimal)? d. what is the probability that bob receives no tweets during the first 30 minutes of his lunch hour (to 4 decimals)?