Sum double only

Given an array of objects, write a method that returns sum of objects of double type.
Expected input and output
SumDoubleOnly(["abc", 5.6, 14, 'c', true, 'x', false, 567, 2.22]) → 7.82
using System;

namespace CSharpExercises.Exercises.Loops
{
    class SumDoubleOnlyTask
    {
        static double SumDoubleOnly(object[] obj)
        {
            double sum = 0.0;
            for (int i = 0; i < obj.Length; i++)
            {
                if (obj[i] is double)
                {
                    sum += (double)obj[i];
                }
            }

            return sum;
        }

        static void Main(string[] args)
        {
            Console.WriteLine(SumDoubleOnly(new object[] { 8.9, "dog", 6, 'c', null, 15.99, 745, true })); // 24.89
        }
    }
}