question_answer 57)

A class has 15 students whose ages are 14, 17, 15, 14, 21, 17, 19, 20, 16, 18, 20, 17, 16, 19, 20 years. One students is selected in such a manner that each has the same chance of being chosen and the age X of the selected students is recorded. What is the probability distribution of the random variable X? Find mean, variance and S.S. of X. 

Answer:

Here X = 14, 15, 16, 1, 18, 19, 20, 21 and       P(X = 14) =       P(X = 16) =       P(X = 18) =       P(X = 20) =       Probability distribution                                                   Now                   and                   mean (X) = E(X) =             Var (X) = E (X2) ? [(E(X)]2                                        =2.19