9 The number of telephone calls coming into a business s switchboard averages 4 calls per minute Let x be the number of calls received 10 points A This is a B Find P x 0 distribution C Find the probability there will be at least 1 call a given 1 minute period D Find the probability there will be exactly 4 calls in a given 1 minute period E Calculate the mean and standard deviation for x the number of call received per minute at this switchboard