求大神帮忙解决一下附件里的第三小题，主要是如何用SPSS求解，如果可以的话请尽量详细点。在此万分感谢！
Table 2.5 contains weight measurements on a group of anorexic girls who
received cognitive-behavioral therapy (CBT). The weight was measured
in pounds before the treatment and after 12 weeks of treatment.

（数据见附件SPSS.xls）

（1） Assuming normality of the weight changes, use the paired samples
t-test box to generate a 95% CI for the mean weight change over
time.

（2）Generate the same results via a one-sample t-test for testing the
null hypothesis that the group’s mean weight change is zero.

（3）Assess whether there is tracking in the data, i.e., do those girls
who start on a low weight also tend to have a relatively low weight
after therapy?