The probability that an event happens is 1/5. Select all statements that are true about the probability that this event does not happen. Select all that apply.

Explanation

The event either happens or it does not, and between them those two cases cover everything, so their probabilities total 1 and the case that is left over comes to 1 - 1/5 = 4/5, four times the share held by the event itself. Taking 1 away from the denominator to get 1/4 changes how many parts the whole is cut into rather than removing a share from the whole, and 1/4 together with 1/5 does not make a whole.