### Question:
SystematicSampling { public static double mean(FlatDataCollection flatDataCollection) { return SimpleRandomSampling.mean(flatDataCollection); }  static FlatDataCollection randomSampling(FlatDataList idList, int n, boolean randomizeRecords); static double mean(FlatDataCollection flatDataCollection); static double xbarVariance(FlatDataCollection flatDataCollection); static double xbarStd(FlatDataCollection flatDataCollection);  }### Answer:
@Test public void testMean() { logger.info("mean"); FlatDataCollection flatDataCollection = generateFlatDataCollection(); double expResult = 103.41666666667; double result = SystematicSampling.mean(flatDataCollection); assertEquals(expResult, result, Constants.DOUBLE_ACCURACY_HIGH); }