Condition Kids
Write an expression in 'visibleIf' to show/hide your question(s)
Survey.Survey.cssType = "bootstrap";
Survey.defaultBootstrapCss.navigationButton = "btn btn-green";

var json = { showQuestionNumbers: "off",
     questions: [
    { type: "radiogroup", name: "haveKids", title: "Do you have a kid(s)?", isRequired: true, choices:["Yes", "No"], colCount: 0},
    { type: "dropdown", name: "kids", title: "How many kids do you have", visibleIf: "{haveKids}='Yes'",
        isRequired: true, choices:[1, 2, 3, 4, 5] }, 
    { type: "dropdown", name: "kid1Age", title: "The first kid age:", visibleIf: "{haveKids}='Yes' and {kids} >= 1",
        isRequired: true, choices:[1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16]},
    { type: "dropdown", name: "kid2Age", title: "The second kid age:", visibleIf: "{haveKids}='Yes' and {kids} >= 2",
        isRequired: true, startWithNewLine: false, choices:[1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16]},
    { type: "dropdown", name: "kid3Age", title: "The third kid age:", visibleIf: "{haveKids}='Yes' and {kids} >= 3",
        isRequired: true, startWithNewLine: false, choices:[1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16]},
    { type: "dropdown", name: "kid4Age", title: "The fourth kid age:", visibleIf: "{haveKids}='Yes' and {kids} >= 4",
        isRequired: true, startWithNewLine: false, choices:[1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16]},
    { type: "dropdown", name: "kid5Age", title: "The fifth kid age:", visibleIf: "{haveKids}='Yes' and {kids} >= 5",
        isRequired: true, startWithNewLine: false, choices:[1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16]}
]};

window.survey = new Survey.Model(json);


survey.onComplete.add(function(result) {
    document.querySelector('#surveyResult').innerHTML = "result: " + JSON.stringify(result.data);
});


$("#surveyElement").Survey({ 
    model: survey 
});

<!DOCTYPE html>
<html>
<head>
    <title>Write an expression in &#39;visibleIf&#39; to show/hide your question(s) for plaform jQuery, SurveyJS Library Example</title>
    <script src="https://unpkg.com/jquery"></script>
    <script src="https://surveyjs.azureedge.net/0.96.3/survey.jquery.js"></script>
  
    <link rel="stylesheet" href="https://unpkg.com/bootstrap@3.3.7/dist/css/bootstrap.min.css">
    <link rel="stylesheet" href="./index.css">

</head>
<body>
                <div id="surveyElement">
            </div>
    <div id="surveyResult"></div>

<script type="text/javascript" src="./index.js"></script>

</body>
</html>
.btn-green {
  background-color: #1ab394;
  color: #fff;
  border-radius: 3px;
}
.btn-green:hover, .btn-green:focus {
    background-color: #18a689;
    color: #fff;
}
.panel-footer {
    padding: 0 15px;
    border:none;
    text-align: right;
    background-color: #fff;
}

clearInvisibleValues : Clear values for invsible questions on survey complete, default is false.

survey.clearInvisibleValues = yourValue; survey.render();