 The kind of variables we have described so far are \(\mathbf{Boolean}\), because their \(\mathbf{domain}\) is simply \(\{true,false\}.\) But we can generalize and allow \(\mathbf{discrete}\) random variables, whose values are from any countable domain. For example, \(\PriceTChina\) might be a variable for the price of (a particular, presumably) tea in China, and its domain might be \(\{1,2,3,4,5\}\), where each number here is in US dollars. A third type of variable is \(\mathbf{continous}\); its domain is either the reals, or some subset thereof. 