06. Speed Info

using System;

namespace SpeedInfo
{
    class SpeedInfo
    {
        static void Main()
        {
            double speed = double.Parse(Console.ReadLine());
            string info = "";

            if (speed <= 10)
            {
                info = "slow";
            }
            else if (speed <= 50)
            {
                info = "average";
            }
            else if (speed <= 150)
            {
                info = "fast";
            }
            else if (speed <= 1000)
            {
                info = "ultra fast";
            }
            else if (speed > 1000)
            {
                info = "extremely fast";
            }
            Console.WriteLine(info);
        }
    }
}

Решение с тернарен оператор:

using System;

namespace SpeedInfo
{
    class SpeedInfo
    {
        static void Main()
        {
            double speed = double.Parse(Console.ReadLine());

            string info = speed <= 10 ? "slow" :
                          speed <= 50 ? "average" :
                          speed <= 150 ? "fast" :
                          speed <= 1000 ? "ultra fast" : "extremely fast";

            Console.WriteLine(info);
        }
    }
}