Q:

How to control if a radio button is checked or not? 

I have 3 radio group and 6 radio buttons.  During the form's submit event user should check at least one radio from different radio groups otherwise the submit event returns false but when i try to do this by using below implementation it always return false so i'am not able to post this form now.  What can be the problem ? 
HTML
<form id="internshipStage2Form" method="POST" action="form2.php">
    <table id="companyInformation" border="1">
        <tr>
            <td valign="middle" align="center">
                <label id="" for="">Did the engineering students work as trainees in the company in the previous years?</label>
            </td>
            <td valign="middle" align="center">
                Yes<input class="radioInput" id="g1Positive" type="radio" name="g1" value="YES"/>
                No<input class="radioInput" id="g1Negative" type="radio" name="g1" value="NO"/>
            </td>
        </tr>
        <tr>
            <td valign="middle" align="center">
                <label>Are the company owners and the top managers are your relatives ? </label>
            </td>
            <td valign="middle" align="center">
                Yes<input class="radioInput" id="g2Positive" type="radio" name="g2" value="YES"/>
                No<input class="radioInput" id="g2Negative" type="radio" name="g2" value="NO"/>
            </td>
        </tr>
        <tr>
            <td valign="middle" align="center">
                <label>Is the firm you declared above on this form same with the firm you intern firstly?</label>
            </td>
            <td valign="middle" align="center">
                Yes<input class="radioInput" id="g3Positive" type="radio" name="g3" value="YES"/>
                No<input class="radioInput" id="g3Negative" type="radio" name="g3" value="NO"/>
            </td>
        </tr>
    </table>
    <input id="sendButton" type="submit" name="sendButton2" value="SEND FOR APPROVEMENT"/>
</form>

JS
$('#internshipStage2Form').submit(function(){  
       var reqRadioFlag = 1;

       $('input:radio').each(function(){
            if(!$(this).is(':checked')){
              reqRadioFlag = 0;
              return false;
            } 
        });

        if(reqRadioFlag === 0){
           alert("Please fill all requiredd areas !"); 
           return false;
       }
});

A:

Try this
$('#internshipStage2Form').submit(function(event){  
    if($('input:radio:checked').length < 3)
    {
        alert("Please fill all requiredd areas !"); 
        return false;
    }
});

DEMO

