Since version 4 the .NET libraries include the StatisticFormula
class which provides T-Tests. This class is available in the namespaces System.Web.UI.DataVisualization.Charting
and System.Windows.Forms.DataVisualization.Charting
Link to documentation and usage:
TTestResult result = Chart1.DataManipulator.Statistics.TTestUnEqualVariances(0.2, 0.05, "Series1", "Series2");