The stock prices of two companies at the end of any given year are modeled with random variables X and Y that follow a distribution with joint density function
![](https://www.beanactuary.org/wp-content/uploads/2020/10/eq.33.1-300x76.jpg)
What is the conditional variance of Y given that X = x ?
- 1/12 Correct Answer
- 7/6
- x + 1/2
- x2 – 1/6
- x2 + x + 1/3
Solution: A
Let f1(x) denote the marginal density function of X. Then
![](https://www.beanactuary.org/wp-content/uploads/2020/10/eq.33.2.jpg)