Use the probability distribution to complete parts (a) and (b) below. 0 1 2 6 7 The number of school-related extracurricular activities per student Activities 3 4 5 Probability 0.059 0.122 0.163 0.177 0.214 0.128 0.084 0.053 (a) Find the mean, variance, and standard deviation of the probability distribution. The mean is 3.4. (Round to one decimal place as needed.) The variance is (Round to one decimal place as needed.)