Get a Weighted Random Number

GetWeightedRandomNumber.cs

    public class Unit
    {
        public string Item { get; set; }
        public int Weight { get; set; }
    }

    public class Program
    {
        public static Unit GetWeightedRandomNumber(List<Unit> list)
        {
            var sorted = list.OrderByDescending(x => x.Weight);
            int totalWeight = sorted.Sum(x => x.Weight);

            int rnd = RNGCryptoRandom.RNGCryptoRandom.GetRandomNumber(totalWeight);

            Unit selected = null;
            foreach (Unit unit in sorted)
            {
                if (rnd < unit.Weight)
                {
                    selected = unit;
                    break;
                }
                rnd = rnd - unit.Weight;
            }

            return selected;
        }
    }

The GetRandomNumber() method is found here:
https://gist.github.com/sachintha81/a4613d09de6b5f9d6a1a99dbf46e2385