ព័ត៌មានវិទ្យា កោះត្រល់

In the survey of 500 TV watchers ,we got the following information 280 watch football, 195 watch hockey, 115 watch basketball, 45 watch football and basketball, 70 watch football and hockey, 50 watch hockey and basketball, and 50 do not watch any of all three games. how many people in the survey watch all three games? how many people watch exactly one game? Solution  Let F denote the set of people who watch Football. Let B denote the set of people who watch Basketball. Let H denote the set of people who watch Hockey. Let X denote all people in the survey Then   if you are not certainly understanding well you can find the step of two people first as