(a) Prefer more to less, meaning that they will always like to have more wealth.

(b) Be risk averse, meaning that they dislike risk as measured by the standard deviation of wealth.

(c) Have a positively sloped utility function, so the gradient or first derivative of the utility function is always positive.

(d) Have a utility function that increases at a diminishing rate. So the shape is concave down like a frown, or the second derivative is always negative.

(e) Have a utility function that rises until it reaches the satiation point, then it falls because too much wealth causes problems.

(a) All rational people prefer more wealth to less.

(b) Mr Blue is risk averse.

(c) Miss Red is risk neutral.

(d) Mrs Green is risk averse.

(e) Mrs Green may enjoy gambling.

(a) Mr Blue prefers more wealth to less. Mrs Green enjoys losing wealth.

(b) Miss Red has the same utility no matter how much wealth she has.

(c) Mr Blue is risk averse.

(d) Miss Red is risk averse.

(e) Mrs Green is risk loving.

(a) Mr Blue and Miss Red prefer more wealth to less.

(b) Mrs Green enjoys losing wealth.

(c) Mr Blue is risk averse.

(d) Miss Red is risk neutral.

(e) Mrs Green is risk averse.

(a) Neither Miss Red nor Mrs Green would appear rational to an economist.

(b) Mrs Green is satiated when she has $25 of wealth. That is her bliss point.

(c) Mrs Green is risk loving when she has between zero and $25 of wealth, same as Mr Blue.

(d) Mrs Green is risk averse when she has between $25 and $50 of wealth.

(e) Mrs Green is risk loving when she has between $50 and $100 of wealth, same as Mr Blue.

(a) Mr Blue's expected utility of wealth from gambling is 5 while refusing is 7.07. So the gamble makes him less happy.

(b) Mrs Green's expected utility of wealth from gambling is 7.07 while refusing is 5. So the gamble makes her more happy.

(c) Mr Blue's certainty equivalent of the risky gamble is $25. This is less than his current wealth of $50 which is why he would refuse.

(d) Miss Red's certainty equivalent of the risky gamble is $50. This is equal to her current wealth of $50 which is why she is indifferent to gambling or not.

(e) Mrs Green's certainty equivalent of the risky gamble is $70.71. This is more than her current wealth of $50 which is why she would accept.

(a) Mr Blue's expected utility of wealth from gambling is 7.5 while refusing is 8.54. So the gamble makes him less happy.

(b) Miss Red's expected utility of wealth from gambling is 5 and refusing is also 5. So the gamble doesn't affect her happiness at all.

(c) Mr Blue's certainty equivalent of the risky gamble is $25. This is less than his current wealth which is why he would refuse.

(d) Miss Red's certainty equivalent of the risky gamble is any wealth. She's indifferent since she always has the same level of happiness.

(e) Mrs Green's certainty equivalent of the risky gamble is $25. This is less than her current wealth which is why she would refuse.

(a) Mr Blue's expected utility of wealth from gambling is 7.5 while refusing is 6.25. So the gamble makes him more happy.

(b) Miss Red's expected utility of wealth from gambling is 7.5 and refusing is also 7.5. This is why she is indifferent.

(c) Mr Blue's certainty equivalent of the risky gamble is $70.71. So he would pay to take part in the gamble.

(d) Miss Red's certainty equivalent of the risky gamble is $50.

(e) Mrs Green's certainty equivalent of the risky gamble is $70.71. She would enjoy taking part in the gamble.

(a) Mr Blue would enjoy the gamble.

(b) Miss Red would be indifferent to gambling or not.

(c) Mrs Green would dislike the gamble.

(d) Mr Blue's certainty equivalent of the risky gamble is $70.71. This is more than his current wealth which is why he would like to gamble.

(e) Miss Red's certainty equivalent of the risky gamble is $50. This is the same as her current wealth which is why she is indifferent to gambling or not.