Why it is showing error?

Question

While I was trying to solve a function about age it was showing wrong.What is the prblm here?
var age=26;
var ageStat=(age<10)?"Child":(age<18)?"young":(age<40)?"Mature":(age>40)?"Old";
document.write(ageStat);

Answer 1

// the last one has to be an answer
var age=26;
var ageStat=(age<10)?"Child":(age<18)?"young":(age<40)?"Mature":"Old";
document.write(ageStat);

Answer 2

Thanks a lot