Exam P：Probability機率題庫下載題庫

57. The warranty on a machine specifies that it will be replaced at failure or age 4, whichever occurs first. The machine’s age at failure, X, has density function

 Let Y be the age of the machine at the time of replacement.
Calculate the variance of Y.
(A) 1.3
(B) 1.4
(C) 1.7
(D) 2.1
(E) 7.5