Chapter 13 - Counting and Probability - 13.3 Probability - 13.3 Asses Your Understanding - Page 866: 54

$0.835$

We know that $P(\text{an event happens})=1-P(\text{an event doesn't happen}).$ Hence, here (with $16.5\%=0.165$) we have $P(\text{not in engineering})=1-P(\text{in engineering})\\ P(\text{not in engineering})=1-0.165\\ P(\text{not in engineering})=0.835$