JavaScript show only part of elements, random generate

I'm trying to make HTML game, which part is set of answers. I don't want whole set to be shown at one session, i want it to be chosen random (from 30 only 6 are shown).

<div id = "answers">
        <li class = "paris"><p> Champ Elysees </p></li>
        <li class = "london"><p> Tate Modern </p></li>
        <li class = "barcelona"><p> Sagrada Familia </p></li>
        <li class = "paris"><p> Montmartre </p></li>
        <li class = "ny"><p> Fifth Avenue </p></li>
        <li class = "barcelona"><p> Paella </p></li>
        <li class = "barcelona"><p> La Rambla </p></li>
        <li class = "london"><p> Piccadilly Circus </p></li>
        <li class = "paris"><p> Mona Lisa </p></li>
        <li class = "ny"><p> Empire State Building </p></li>
        <li class = "ny"><p> Broadway </p></li>
        <li class = "paris"><p> Musée d'Orsay </p></li>
        <li class = "ny"><p> Wall Street </p></li>
        <li class = "london"><p> Camden Town </p></li>
        <li class = "ny"><p> Big Apple </p></li>
        <li class = "barcelona"><p> La Boqueria </p></li>
    </div>

My question is: how can I hide this elements and show only part of them by random generate?