Susan is an engineering student who decides to take part in three competitions where puzzles need to be solved as quickly as possible by correctly fitting all the pieces of a gadget together in each case. In Competition A, she takes 125 seconds to complete the puzzle, in Competition B she takes 140 seconds, and in Competition C she takes 118 seconds. Overall completion times for participants in Competition A are normally distributed with a mean of m = 119 seconds and a standard deviation s = 7 seconds. Completion times for participants in Competition B are normally distributed with a mean of m = 165 seconds and a standard deviation s = 15 seconds.

Completion times for participants in Competition C are normally distributed with a mean of m = 109 seconds and a standard deviation s = 8 seconds. In which competition was Susan’s performance better, relative to others who took part in that competition? Justify your answer, quoting relevant statistics as part of your explanation.