entheticis

50. In a group of 10 registered voters what is the probability that between 2 and five voters prefer
candidate B?
A. 0.788
B. 0.667
C. 0.633
D. 0.452
E. 0.534

Solution: P=P(2)+P(3)+P(4)+P(5)

不太理解这个…… 哪位大侠解释下哈！