Perform a significance test

Companies are interested in the demographics of those who listen to the radio programs they sponsor. A radio station has determined that only 20% of listeners phoning in to a morning talk program are male. the station management wonders if adding a male host to the program will increase the proportion of callers who are male. After adding a male host, the station records the gender of 200 people who phone in to the program during a particular week. The station is willing to view these 200 callers as an SRS from the population of all those who call in to the program. In fact during this particular week 50 of the 200 callers were male. Does this provide significant evidence to suggest that the proportion of male callers has increased from 20%? support your answer with an appropriate probability calculation.