Не самое изысканное решение задачи, но числа проходят проверку, а валидацию нет. В чем трабл?
package com.javarush.task.task04.task0416;
/*
Переходим дорогу вслепую
*/
import java.io.*;
public class Solution {
public static void main(String[] args) throws Exception {
BufferedReader reader = new BufferedReader(new InputStreamReader(System.in));
String sNom = reader.readLine();
double t = Double.parseDouble(sNom);
if (0 <= t & t<= 2.9 || 5 <= t & t<= 7.9 || 10 <= t & t<= 12.9 || 15 <= t & t<= 17.9 || 20 <= t & t<= 22.9 || 25 <= t & t<= 27.9 || 30 <= t & t<= 32.9 || 35 <= t & t<= 37.9 || 40 <= t & t<= 42.9 || 45 <= t & t<= 47.9 || 50 <= t & t<= 52.9 || 55 <= t & t<= 57.9)
{
System.out.println("зелёный");
}
if (3 <= t & t<= 3.9 || 8 <= t & t<= 8.9 || 13 <= t & t<= 13.9 || 18 <= t & t<= 18.9 || 23 <= t & t<= 23.9 || 28 <= t & t<= 28.9 || 33 <= t & t<= 33.9 || 38 <= t & t<= 38.9 || 43 <= t & t<= 43.9 || 48 <= t & t<= 48.9 || 53 <= t & t<= 53.9 || 58 <= t & t<= 58.9)
{
System.out.println("жёлтый");
}
if (4 <= t & t<= 4.9 || 9 <= t & t<= 9.9 || 14 <= t & t<= 14.9 || 19 <= t & t<= 19.9 || 24 <= t & t<= 24.9 || 29 <= t & t<= 29.9 || 34 <= t & t<= 34.9 || 39 <= t & t<= 39.9 || 44 <= t & t<= 44.9 || 49 <= t & t<= 49.9 || 54 <= t & t<= 54.9 || 59 <= t & t<= 59.9)
{
System.out.println("красный");
} //напишите тут ваш код
}
}