问题如下图：
选项：
A. 
B. 
C. 
解释：
老师，这道题的表格 看不懂是什么意思，麻烦解答，谢谢！
星星_品职助教 · 2019年09月13日
同学你好，
你说的表格问题涉及到对累计概率函数CDF的理解。这是一个比较重要的基础概念。累积概率函数中的“累积”意思是所有概率从小到大的累积加总。也就是图中F(X)=P（X≤x）的意思。
具体来说，当X=1时，因为只有一个x，所以即便是“累积”也是只累积自己，所以F(1)就是当X=1时的概率，0.15。但当X=2时，F（2）就“累积”了两个概率，分别是X=1的概率和X=2的概率，所以通过F（2）=0.25就知道这个0.25是X=1的概率（0.15）加上X=2的概率（未知）之和，所以单独的X=2的概率就是F（2）-F（1）=0.25-0.15=0.10.
同理，F（3）=0.5说明了X=3的概率就是0.5-0.25=0.25。
用数学语言来说，就是累积概率函数“累积”了对应取值左面的所有面积。
根据此逻辑，可得出x=4的概率为F(4)-F（3）=0.6-0.5=0.1
以上就是累积概率函数的解释和这题表格的用法。
不确定这道题你是否有别的问题，就一起说完吧，这道题的第二个考点是加法法则在互斥性下的应用，由于X一次只能取一个值，所以X取2或4不可能同时发生，为互斥事件，即P（AB）=0。对应的公式即变为P（A or B）=P(A)+P（B）=P（2）+P（4）。由于通过表格已经得到P（2）=0.1，P（4）=0.1，所以P（2 or 4）就为0.2.
CDF是个很重要的概念，“累积”的概念意味着“左侧面积”的这个思想之后还会有多次应用，建议会去再听一下这部分的视频巩固。加油
NO.PZ2017092702000091 问题如下 The cumulative stribution function for a screte ranm variable is shown in the following table. The probability thX will take on a value of either 2 or 4 is closest to: A.0.20. B.0.35. C.0.85. A is correct. The probability thX will take on a value of 4 or less is: F(4) = P(X ≤ 4) = p(1) + p(2) + p(3) + p(4) = 0.60. The probability thX will take on a value of 3 or less is: F(3) = P(X ≤ 3) = p(1) + p(2) + p(3) = 0.50. So, the probability thX will take on a value of 4 is: F(4) – F(3) = p(4) = 0.10. The probability of X = 2 cfounusing the same logiF(2) – F(1) = p(2) = 0.25 – 0.15 = 0.10. The probability of X taking on a value of 2 or 4 is: p(2) + p(4) = 0.10 + 0.10 = 0.20. 为什么不是0.1+0.1-0.01=0.19
NO.PZ2017092702000091 问题如下 The cumulative stribution function for a screte ranm variable is shown in the following table. The probability thX will take on a value of either 2 or 4 is closest to: A.0.20. B.0.35. C.0.85. A is correct. The probability thX will take on a value of 4 or less is: F(4) = P(X ≤ 4) = p(1) + p(2) + p(3) + p(4) = 0.60. The probability thX will take on a value of 3 or less is: F(3) = P(X ≤ 3) = p(1) + p(2) + p(3) = 0.50. So, the probability thX will take on a value of 4 is: F(4) – F(3) = p(4) = 0.10. The probability of X = 2 cfounusing the same logiF(2) – F(1) = p(2) = 0.25 – 0.15 = 0.10. The probability of X taking on a value of 2 or 4 is: p(2) + p(4) = 0.10 + 0.10 = 0.20. 老师这道题里为什么要求x小于等于4的概率和x小于等于2的概率，直接用x=4和2的概率相加不行吗
NO.PZ2017092702000091问题如下The cumulative stribution function for a screte ranm variable is shown in the following table. The probability thX will take on a value of either 2 or 4 is closest to:A.0.20.B.0.35.C.0.85.A is correct. The probability thX will take on a value of 4 or less is: F(4) = P(X ≤ 4) = p(1) + p(2) + p(3) + p(4) = 0.60. The probability thX will take on a value of 3 or less is: F(3) = P(X ≤ 3) = p(1) + p(2) + p(3) = 0.50. So, the probability thX will take on a value of 4 is: F(4) – F(3) = p(4) = 0.10. The probability of X = 2 cfounusing the same logiF(2) – F(1) = p(2) = 0.25 – 0.15 = 0.10. The probability of X taking on a value of 2 or 4 is: p(2) + p(4) = 0.10 + 0.10 = 0.20.如题。。。。。。。。
The probability that X will take on a value of either 2 or 4 is closest to 是同时取2和4的概率的意思？