Question: A police commissioner is interested in the number of phone calls into the police dispatcher that result in criminal charges actually being filed. For a random sample of 190 nights (7 pm to 7 am), the following information was obtained where x = number of calls resulting in criminal charges and f = frequency with which this many calls occurred (i.e., number of nights).

Assuming these 190 nights are representative of the population of all nights in this police precinct, what do you estimate the probability is that on a randomly selected night, there will be from 27 to 31 (including 27 and 31) calls to the dispatcher that result in criminal charges being filed?