Select an option makes a checkbox checked

Fixed, my bad.. guys enclose your jQuery code in document.ready(func... 

Note: This is when you have your js code in a sepearate .js file

i.e. 

$(document).ready(function(){
$("#select").change(function(){
var selected=$(this).val();
$('[id^="chkbox-"]').prop('checked', false);
$("#chkbox-"+selected).prop('checked', true);
});
});

Within a single file of .html just enclose this code inside and don't forget to add cdn of latest jQuery you can find at https://releases.jquery.com/ in tag of your html document( i.e. .html file)

Thank you very much! @Sachin Singh it worked1

@Sachin Singh thanks here last is the paragraph element with a bootstrap class "lead" on it , okay what I want to do is to select a city from the select tag and what happens is that after the selection of city related checkbox gets checked. 
Here see I have selected the Lahore option and Karachi checkbox gets checked which is wrong this is the issue still persisting tried both JavaScript and jQuery

Again the code:

Select Tag:

Select
Lahore
Karachi

CheckBox:

Lahore
Karachi

JavaScript:

function Select()
{
var Option=document.getElementById("select").value;
if(Option="Lahore"){
document.getElementById("chkbox-lahore").checked = true;
}
else{
document.getElementById("chkbox-karachi").checked = true;
}
}
jQuery:
$("#select").change(function(){
var selected=$(this).val();
$(".chkbox"+selected).prop('checked', true);
});