How to get a random int between 1-100 where result is skewed towards X?

Question

I want to generate a random age, lets say between 1-100. My "target" age is around 40, so I want most generated ages to be roughly 30-50, but still a few generated outside this smaller range. Is there anyway to do this?

Preferably using C# library.

Answer 1

You don't need a C# Library. You can achieve this via Math.

using System;

class Program
{
    static void Main()
    {
        int targetAge = 40;
        int minAge = 1;
        int maxAge = 100;

        int generatedAge = GenerateRandomAge(targetAge, minAge, maxAge);
        Console.WriteLine($"Generated Age: {generatedAge}");
    }

    static int GenerateRandomAge(int targetAge, int minAge, int maxAge)
    {
        Random random = new Random();
        double mean = targetAge; // Mean of the distribution
        double standardDeviation = 8; // Standard deviation controls the spread of values
        double u1 = 1.0 - random.NextDouble();
        double u2 = 1.0 - random.NextDouble();
        double randStdNormal = Math.Sqrt(-2.0 * Math.Log(u1)) * Math.Sin(2.0 * Math.PI * u2);
        double randNormal = mean + standardDeviation * randStdNormal;
        int generatedAge = (int)Math.Round(Math.Clamp(randNormal, minAge, maxAge)); // Ensure the generated value is within the specified range
        return generatedAge;
    }
}

Refer the working code here