The SAS System        22:14 Thursday, August 25, 2011   1

                                        Obs    concentration

                                         1           58 
                                         2           63 
                                         3           48 
                                         4           52
                                         5           68

                                           The SAS System        22:14 Thursday, August 25, 2011   2

                                        The TTEST Procedure

                                      Variable:  concentration

                    N        Mean     Std Dev     Std Err     Minimum     Maximum

                    5     57.8000      8.0747      3.6111     48.0000     68.0000

                       Mean       95% CL Mean        Std Dev      95% CL Std Dev

                    57.8000     47.7740  67.8260      8.0747      4.8378  23.2030

                                       DF    t Value    Pr > |t|

                                        4       2.16      0.0969