Recall our guide:

The event E consists of all outcomes in S which are favorable.

To make sense of this, we first need a sample space S. Since we are not told what the experiment does, there is no fixed choice for S. Here are two choices, together with the solution for each:

Choice 1: S = {covered by employer's plan, covered by own plan, covered by spouse's plan, not covered}

The favorable outcomes are those in which the worker is not covered by an individual plan. There are two of those: covered by employer's plan, and not covered . Thus,

E = {covered by employer's plan, not covered}.

Choice 2: S = {covered by an individual plan, not covered by an individual plan}

There is only one favorable outcomes: not covered by an individual plan . Thus,

E = {not covered by an individual plan}.