<span style="color:#0e0e0e;"><i><b>One percent of the population is billionaires.</b></i></span><br/><br/><span style="color:#0e0e0e;"><i><b>One percent of the population are billionaires.</b></i></span><br/><br/> When saying They, it's implied that 2 people are no longer together, so the question should be Are <br/><br/><span style="color:#0e0e0e;"><i><b>They are no longer together. Who's no longer together.</b></i></span><br/><br/><span style="color:#0e0e0e;"><i><b>They are no longer together. Who are no longer together.</b></i></span>