Solution of Program on http://ronitmukherjee.com/practice-javascript-programs-for-interview/#RMJPQ7

RMPJPQ7.js

//https://jsfiddle.net/mukherjeeronit/9rxwt0n5/

function main(students){
  var namesOfStudent = [];
  
  for(var i=0; i<students.length; i++){
      var student = students[i];
      
      if(student.contact_numbers.length > 1 && student.age < 18){
          namesOfStudent.push(student.name);
      }
  }
  
  console.log("List of Names:- ", namesOfStudent);
}

var input = [{
    name: "Ajay",
    age: 12,
    contact_numbers:[
      8647896541,
      7489651258
    ]
  },
  {
    name: "Amit",
    age: 16,
    contact_numbers:[
      8647896541
    ]
  },
  {
    name: "Shikha",
    age: 18,
    contact_numbers:[
      8647896541,
      9745896512,
      6589784589
    ]
  },
  {
    name: "Manish",
    age: 62,
    contact_numbers:[]
  }
];

main(input);