The random variable X represents the number of persons in a Singapore family chosen at random and has the following probability distribution: X Px 1 0.34 2 0.44 3 0.11 4 0.06 5 0.03 6 0.02 [1] The average family size in Singapore (do not round answer) (a) 21 (b) 1.78 (c) 2.39 (d) 2.06 (in) [1] The standard deviation of the number of persons in a Singapore family is (a) 2.35 (b) 1.13 (c) 1.28 (d) 5.52 (in) [1] In any randomly selected Singapore family, the probability that X is at most 3 is (a) 0.22 (b) 0.11 (c) 0.89 (d) 0.78 (iv) [1] If a Singapore family has at most 3 persons, the probability that there are exactly 2 persons is (a) 0.44 (b) 0.49 (c) 0.56 (d) 0.62 (v) [2] What is the probability that 2 randomly selected Singapore families will have at least 10 people in total? (a) 0.0049 (b) 0.0021 (c) 0.0058 (d) 0.0037