单选题 A random variable X is continuous and bounded between zero and five, X:(0≤X≤5). The cumulative distribution function (cdf) for X is F(X)=X/5. Calculate P(2≤X≤4).

A、

A. 1.00.
B、

B. 0.25.
C、

C. 0.40.

【正确答案】 C

【答案解析】For a continuous distribution, P(a≤X≤b)=F(b)-F(a). Here, F(4)=0.8 and F(2)=0.4. Note also that this is a uniform distribution over 0≤X≤5 so P (2≤X≤4)=(4-2)/5=40%.