A union of events A,B,C, . . . is an event consisting of all the outcomes in all
these events. It occurs if any of A,B,C, . . . occurs, and therefore, corresponds
to the word “or”: A or B or C or ... (Figure 2.1a).
The Attempt at a Solution
I'm confused at "It occurs if any of A,B,C, . . . occurs"
If the union of events A,B,C... is an event consisting of all outcomes in all of these events, then doesn't that imply that A and B and C and ... have to occur, not A or B or C or ..?
I understand that this is their definition and they can define it anyway they want to, but it seems off for me.
One way I can possibly rationalize this is: say x is an outcome of a union b. and x is an outcome of a but not b. Since x is an outcome of a union b, if x has occured, the event a union b has occured. But also the event A has occured
am I on the right track?