问题
单项选择题
Which of the following statement concerning about the probability concepts is TRUE（）
A. A joint probability is the probability that two or more events happen concurrently.
B. Subjective probability is a probability drawing on observation.
C. A random variable is a quantity whose outcomes are certain.
答案
参考答案：B
解析：
Choice C. A random variable is a quantity whose outcomes are uncertain.