In the article “Helmet use and risk of head injuries in alpine skiers and snowboarders”

published in the JAMA (Sulheim et al., 2005), the authors reported the data given in Table 7.36 on the skiing ability for skiers and snowboarders for individuals suffering head injuries and an uninjured control group. Use the data in Table 7.36 to answer the following questions.

(a) Does the data in Table 7.36 support the use of a chi-squared test of independence?

(b) Test the hypothesis that a skier’s ability is independent of group at the ???? = 0.05 level.