Example 4.4.3.----Behrens-Fisher Problem

x1={180, 192, 217, 221, 171, 192, 213, 192, 170, 201};
x2={245, 260, 276, 299, 239, 262, 278, 255, 244, 276};
y1={181, 158, 184, 171, 181, 181, 177, 198, 180, 177, 176, 192, 164};
y2={305, 237, 300, 273, 297, 308, 301, 308, 286, 299, 317, 312, 265};