My View code in MVC: I want to disable the Dropdownlist in View code when the checkbox is checked.

function SaveNewGroup() {



    var group = RetrieveGroup();

    var IsChecked = $(IsAssociation).is(:checked);

    var url = (IsChecked) ? /Administration/SaveNewGroupforIsAssociation : /Administration/SaveNewGroup;

    var userID = $('#groupunderwriter').val();



    $.ajax({

        type: POST,

        url: url,

        data: group,

        datatype: json,

        success: function (groupID) {

            if (groupID > 0) {



                GetGroups();



                $('#groupdialog').dialog('close');

            }

            else {

                alert(Unable to create Group.);

            }

        }

    });

}

Check box:

<tr>

            <td>

                <label>Is Association</label></td>

            <td>

                <input type =checkbox id=IsAssociation/>

            </td

>

and my dropdownlist:

<tr>

<td>Underwriter Name:</td>

        <td>

            <select id=groupunderwriter style=width:150px;>

                <option value =0></option>

               @foreach (RMS.UserService.User u in Model.GroupUnderWriters)

                {

                    <option [email protected]>

                        @if(Model.MasterGroupAttribute.UserID == u.UserID)

                   {

                       @:selected=selected

                   }

                   >@(u.FirstName +   + u.LastName )</option>



                }

            </select>

        </td>



    </tr>

How to disable the dropdownlist when the checkbox is checked or enable it when not checked?