关于Expected utility框架下风险偏好与Lottery选择的疑问咨询

（注：原题附带对应图示，但未提供截图）

The figure below describes John's preferences over lotteries for three prizes- $1, $2, and $3, where p1 is the probability of winning $1, and p3 is the probability of winning $3. Assume that John is an expected utility maximizer.

a) Is John risk averse?

b) Suppose it is additionally known that John prefers a lottery that pays $2 with probability 1/2 and $3 with probability 1/2 to a certain payment of $2.50. Which of the following two lotteries will John prefer? Explain briefly.

• Lottery A: A payment of $2 with probability 1.
• Lottery B: A lottery that pays $2.50 with probability 0.35 and $1 with probability 0.65.

我实在搞不懂这个问题，一开始我算了期望效用。根据题目里的描述，因为John偏好那个50%概率得$2、50%概率得$3的彩票，而不是确定的$2.50，那他肯定是风险偏好型的对吧？

不过当我计算Lottery A和Lottery B的期望效用时，算出来A的EU是2，B的是1.525，这时候我就不知道该怎么下结论了。他虽然是风险爱好者，但Lottery B的期望效用反而比A低，那他应该不会选B吧？我觉得正确答案应该是他会选Lottery A，这个判断对吗？

备注：内容来源于stack exchange，提问作者Disintegrators