In this case, we'll have to carry out several steps to find the solution.
Step 01:
Data:
Pilot error = 628
Other human error = 95
Weather = 238
Mechanical problems = 265
Sabotage = 218
relative frequency = ?
Step 02:
relative frequency:
total plane crashes = 1444
Pilot error = 628 / total * 100% = 628 / 1444 * 100 %= 43.5 %
Other human error = 95 / 1444 * 100% = 6.6 %
Weather = 238 / 1444 * 100% = 16.5 %
Mechanical problems = 265 / 1444 * 100% = 18.4%
Sabotage = 218 / 1444 * 100% = 15.1 %
The answer is:
Pilot error = 43.5 %
Other human error = 6.6 %
Weather = 16.5 %
Mechanical problems = 18.4%
Sabotage = 15.1 %