One hundred teachers attended a seminar on mathematical problem solving. The attitudes of a representative sample of 1212of the teachers were measured before and after the seminar. A positive number for change in attitude indicates that a teacher's attitude toward math became more positive. The 1212change scores are as follows:

2;9;1;2;0;5;-4;1;1;6;4;2

(a) What is the mean change score?

Round your answer to two decimal places.

x=

(b) What is the standard deviation for this sample? Round your answer to two decimal places.

s=

(c) What is the median change score?

(d) Find the change score that is 2.2 standard deviations below the mean. Round your answer to two decimal places.