I attempted the following problem and came to the following conclusion. The question was asking the probability that either a jet fire or flash fire occurs.

EVENT A=ignites immediately (jet fire)0.01

EVENT B=delayed ignition (flash fire) 0.01

The question is asking for union of these two events right?

P(AUB)=P(A)+P(B)-P(AnB)

since the two events are mutually exclusive we can conclude that P(AnB)=0

which leaves that P(AUB)=0.01+0.01=0.02

I keep getting told by my peers that I'm wrong but I don't know why. Is there something wrong about my approach?