The Ca content of a powdered mineral sample was examined four times by two methods believed to have similar precision. The results are shown below. Explain are the mean values for these two methods the same at the 90% confidence level?
Method 1: Methhod 2:
0.0271 0.0271
0.0282 0.0268
0.0279 0.0263
0.0271 0.0274