jQuery corresponding radio button selection

I have some divs, each with a radio button and a drop-down box. What is some simple jQuery to, on selection of the drop-down box, check the radio button within the same div?

<div id="x">
  <%= radio_button_tag "opt", "gene", false %>
  <%= select_开发者_JS百科tag "opt", options_for_select(@genes), { :multiple => false, :class => 'selectors'} %>
</div><br/>

If your HTML looks something like this:

<div class="some-class">
    <input id="r1" type="radio" name="radios">
    <label for="r1">Radio me</label>
    <select>
        <option>one</option>
        <option>two</option>
        <option>three</option>
    </select>
</div>

<div class="some-class">
    <input id="r2" type="radio" name="radios">
    <label for="r2">Radio me</label>
    <select>
        <option>four</option>
        <option>five</option>
        <option>six</option>
    </select>
</div>

<div class="some-class">
    <input id="r3" type="radio" name="radios">
    <label for="r3">Radio me</label>
    <select>
        <option>seven</option>
        <option>eight</option>
        <option>nine</option>
    </select>
</div>

then your JavaScript could look something like this:

$('div.some-class > select').live('change', function ()
{
    $(this).prevAll('input:radio').attr('checked', true);
});

http://jsfiddle.net/mattball/CBGMD/

$('select').bind('click', function() {
    $(this).parent('div').children('input[type=radio]').attr('checked','checked');
});

$('.selectors').change(function() {
    $(this).prev().attr('checked', true);
});