k ak pk 1 100 0.10 2 200 0.25 3 300

题目：

k	ak	pk
1	100	0.10
2	200	0.25
3	300	0.20
4	400	0.25
5	500	0.20

If in an experiment the probabilities of obtaining the values a₁，a₂，a₃，a₄， and a₅are p₁，P₂，P₃，P₄ and P₅，respectively，then the expected value is defined as a₁p₁+a₂p₂+a₃p₃+a₄p₄+a₅p₅．For the values and their corresponding probabilities in the table above，what is the expected value

A. 350
B. 320
C. 300
D. 270
E. 250