Problem # 3 (20 pts). (If you simply write the answers and don't construct the table, you will not obtain credit). The random variable x represents the number of credit cards that adults have along with the corresponding probabilities. Find the mean and standard deviation using a) The definition of standard deviation and b) the Computational formula. X P (X) 0.07 0.68 2 0.21 3 0.03 4 0.01 Total A) mean: 1.30; standard deviation: 0.44 B) mean: 1.23; standard deviation: 0.66 C) mean: 1.30; standard deviation: 0.32 D) mean: 1.23; standard deviation: 0.44