If a study was done to measure the total brain volume of patients that had schizophrenia and also of patients that are normal. Table 1 has the total brain volume of the normal patients and table 2 has the total brain volume of schizophrenia patients. I do not understand how you compute a 90% confidence interval for the difference in total brain volume of normal patients and schizophrenia patients

Table 1: Total Brain Volume (in ) of Normal Patients

1663407, 1583940, 1299470, 1535137, 1431890, 1578698, 1453510, 1650348, 1288971, 1366346, 1326402, 1503005,1474790, 1317156, 1441045, 1463498, 1650207, 1523045, 1441636, 1432033, 1420416, 1480171, 1360810, 1410213,1574808, 1502702, 1203344, 1319737, 1688990, 1292641, 1512571, 1635918

Table 2: Total Brain Volume (in ) of Schizophrenia Patients

1331777, 1487886, 1066075, 1297327, 1499983, 1861991, 1368378, 1476891, 1443775, 1337827, 1658258, 1588132,1690182, 1569413, 1177002, 1387893, 1483763, 1688950, 1563593, 1317885, 1420249, 1363859, 1238979, 1286638,1325525, 1588573, 1476254, 1648209, 1354054, 1354649, 1636119