A school class of 120 students are driven in 3 buses to a symphonic performance. There
are 36 students in one of the buses, 40 in another, and 44 in the third bus. When the
buses arrive, one of the 120 students is randomly chosen. Let X denote the number of
students on the bus of that randomly chosen student. (8%)
(8) Find E(X ) ;
(9) Find Var(X ) .
Let f (x) =1, 0 ≤ x ≤1be the probability density function of random variable X . Find
(8%)
(10) the mean and variance of X ,
(11) the mean and variance of X 2 .
The train 625 arrives in Taichung station at any second from AM 9:00 to AM 9:10 with
equal likelihood (16%)
(22) What is the expected time the train 625 arrives at Taichung?
(23) What is the variance of the time of train 625 arrives at Taichung?
(24) What is the probability that you catch the train if you arrive in Taichung station at
AM 09:07?
(25) What is the expected waiting time for catching the train 625 when you arrive in
Taichung station at AM 08:50?
可觀看題目詳解,並提供模擬測驗!(免費會員無法觀看研究所試題解答)