Workers in 2 different mine groups were asked what they considered to be the most important labour-management problem. In Group A, 200 out of a random sample of 400 workers felt that a fair adjustment of grievances was the most important problem. in Group B, 60 out of a random sample of 100 workers felt that this was the most important problem. Would you conclude that these 2 groups differed with respect to the prpportion of workers who believed that fair adjustment of grievances was the most important problem? Test at a=0.1