Agumball machine contains blue, pink, white and green gum balls. in the machine, 50% of the gumballs are blue, 10% are pink 20% are white 20% are gree. if event a is jane turning the knob of the gumballs machine and a blue gumballs dropping out then the completement of event a is

0.5 (or 50%).

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.