1. The problem statement, all variables and given/known data I realise this is probably an obvious question, but if there are two groups, say group A and group B, where group A was full of old people, and group B full of children. The mean age was 67 for group A and the mean age was 5 for group B. If these two groups joined together to make one big group, what is the new mean? 3. The attempt at a solution is it just ( 67 + 5 ) / 2 so it would be 36?