How do I acces a var from the main time line in to a movieclip?

Question

I'm making a quiz-type animation, since I'm new with ActionScript I had developed my own way to make this work.
I want to add like a meter that shows one out three position depending on the answer given, I had made this animation as a movieclip but now I need it to react according to the answer, so it changes on every question to do that I need to access the variables I'm using in the main time line, how can I access the the main time line variables from the movie clip?
The movie clip (meter) is basically the background and the questions will change and advance on top of that movie clip so it'll change with each answer until you get the final result.
Since I cant attached my FLA file here I could email my it to whom may want to help me, THANK YOU!!!

Answer 1

I kinda of make it work using what you suggested: var meterVar = MovieClip(this.root).userAnswer;, but I have different problems now I'm getting this error: TypeError: Error #1009: Cannot access a property or method of a null object reference.
     at divameter2_fla::MovieClip_1/frame1() and the meter movieclip only change from the original position to the second and stays there even if the first answer supose to sent it to the third or four position. here is the code for the main and movie clip:
Main:
The following code I have it in separate frames, I know is probbably not the best way to do it but I'm new with AS.
Frame 1:
stop();
messageBox.text = "";
var userAnswer:int;
var rbg:Object = rbA.group;
var finalScore:int;
btnCheck.addEventListener(MouseEvent.CLICK, nextBtn);
function nextBtn(evt:MouseEvent):void {
             userAnswer = int(rbg.selectedData);
             if(userAnswer == 0) {messageBox.text = "Please select an option";
             }else{
                 finalScore = userAnswer;
                 gotoAndPlay(2);
Frame 2:
stop();
messageBox.text = "";
var rbbg:Object = rbbA.group;
btnCheckTwo.addEventListener(MouseEvent.CLICK, nextBtnTwo);
function nextBtnTwo (evt:MouseEvent):void {
             userAnswer = int(rbbg.selectedData);
             if(userAnswer == 0) {messageBox.text = "Please select an option";
             }else{
                 finalScore = finalScore + userAnswer;
                 gotoAndPlay(3);
Frame 3:
stop();
messageBox.text = "";
var rbcg:Object = rbcA.group;
btnCheckThree.addEventListener(MouseEvent.CLICK, nextBtnThree);
function nextBtnThree (evt:MouseEvent):void {
             userAnswer = int(rbcg.selectedData);
             if(userAnswer == 0) {messageBox.text = "Please select an option";
             }else{
                 finalScore = finalScore + userAnswer;
                 gotoAndPlay(4);
Frame 4:
stop();
messageBox.text = "";
var rbdg:Object = rbdA.group;
btnCheckFour.addEventListener(MouseEvent.CLICK, nextBtnFour);
function nextBtnFour (evt:MouseEvent):void {
             userAnswer = int(rbdg.selectedData);
             if(userAnswer == 0) {messageBox.text = "Please select an option";
             }else{
                 finalScore = finalScore + userAnswer;
                 gotoAndPlay(5);
Frame 5:
stop();
messageBox.text = "";
var rbeg:Object = rbeA.group;
btnCheckFinish.addEventListener(MouseEvent.CLICK, finishBtn);
function finishBtn (evt:MouseEvent):void {
             userAnswer = int(rbdg.selectedData);
             if(userAnswer == 0) {messageBox.text = "Please select an option";
             }else{
                 finalScore = finalScore + userAnswer;
                 if (finalScore > 4) gotoAndPlay(6);
                 if (finalScore > 9) gotoAndPlay(7);
                 if (finalScore > 13) gotoAndPlay(8);
The las theree frames are the 3 different results and the code they have is only a stop();
The following is the movieclip code:
stop();
var meterVar = MovieClip(this.root).userAnswer;
var btnCheck = MovieClip(this.root).btnCheck;
var btnCheckTwo = MovieClip(this.root).btnCheckTwo;
var btnCheckThree = MovieClip(this.root).btnCheckThree;
var btnCheckFour = MovieClip(this.root).btnCheckFour;
btnCheck.addEventListener(MouseEvent.CLICK, nextBtn);
     function nextBtn (evt:MouseEvent):void {
             if (meterVar == 1) {gotoAndPlay(2);
                 if (meterVar == 2) gotoAndPlay(3);
                 if (meterVar == 3) gotoAndPlay(4);
             }else{ gotoAndPlay (1);
btnCheckTwo.addEventListener(MouseEvent.CLICK, nextBtnTwo);
     function nextBtnTwo (evt:MouseEvent):void {
             if (meterVar == 1) {gotoAndPlay(2);
                 if (meterVar == 2) gotoAndPlay(3);
                 if (meterVar == 3) gotoAndPlay(4);
             }else{ gotoAndPlay (1);
btnCheckThree.addEventListener(MouseEvent.CLICK, nextBtnThree);
     function nextBtnThree (evt:MouseEvent):void {
             if (meterVar == 1) {gotoAndPlay(2);
                 if (meterVar == 2) gotoAndPlay(3);
                 if (meterVar == 3) gotoAndPlay(4);
             }else{ gotoAndPlay (1);
btnCheckFour.addEventListener(MouseEvent.CLICK, nextBtnFour);
     function nextBtnFour (evt:MouseEvent):void {
             if (meterVar == 1) {gotoAndPlay(2);
                 if (meterVar == 2) gotoAndPlay(3);
                 if (meterVar == 3) gotoAndPlay(4);
             }else{ gotoAndPlay (1);
I had attached the almost working FWS file