One hundred teachers attended a seminar on mathematical problem solving. The attitudes of a representative sample of 12 of the teachers were measured before and after the seminar. The differences between their pre-seminar scores and post-seminar scores are shown below. 6 6 10 5 3 288-2 -2 4 5 (a) What is the range of the scores? (b) What is the standard deviation of the scores? Round your answer to the nearest tenth, if necessary.