Bicarbonate levels in samples of horse blood was measured four times by two different methods.

Method 1: 31.40, 31.24, 31.18, 31.43 mM

Method 2: 30.70, 29.49, 30.01, 30.15 mM

Calculate the 95% confidence interval for the mean bicarbonate level for each method. Show your calculations (2 marks).

Is there a significant difference between the two methods at = 0.05. Show your results to support your conclusion (2 marks).