Among fatal plane crashes that occurred during the past 60 years, 650 were due to pilot error, 78 were due to other human error, 156 were due to weather, 286 were due to mechanical problems, and 117 were due to sabotage. (These results are based on data from PlaneCrashInfo.com, and they do not include private aircraft, military aircraft, aircraft carrying 10 or fewer people, or helicopters.) What is the most serious threat to aviation safety, and can anything be done about it?
Use the given categorical data to construct the relative frequency distribution.