A study has been carried out, part of which involved measurement of pure-tone threshold at 4 kHz across a range of ages. Thirty male and 30 female subjects have been used. The data are presented below.                                               Carry out appropriate statistical tests to describe the nature of relationships between age and threshold. Is there a significant difference in the nature of these relationships between the male and female subjects? 这题是分析男女之间的年龄对阈值的关系的显著性差异嘛，是看男女两个年龄对阈值的回归公式的显著性差异吗，那该用什么分析方法来解决呢 What would you predict the threshold to be in 50 year old males and females?