Suppose an investigator is looking at age at menarche (first period) and its relationship to the onset of breast cancer in women. The investigator conducted a thorough literature review and wanted to...

Suppose an investigator is looking at age at menarche (first period) and its relationship to the onset of breast cancer in women. The investigator conducted a thorough literature review and wanted to test out the hypothesis that women with an earlier menarche are less likely to develop breast cancer. Suppose the investigator conducted a population based study and found that the average age at menarche was 12.3 years with a standard deviation of 1.3 years. Assuming the investigator finds that women in the highest 10% of the distribution have a relative risk of 1.4 for developing breast cancer. What age at menarche correlates to this percentile? (Hint: highest 10% means 90th percentile)