Answer: 0.5 (or 50%).
Step-by-step explanation:
The complement of event A Jane turning the knob of the gumballs machine and a non blue gumball droping out.
That is 1 less the probability of event A
The probability of event A is 0.5, then the probability of the complement of A is 1 - 0.5 = 0.5.
You can verifiy it because the complement of event A is a gumball pink, white or green droping out of the gumballs machine.
So, you can also sum up the probabilities of those three independent events: 0.1 + 0.2 + 0.2 = 0.5, as obtained above.