Answer:
The last part of the question is missing:
- Sue is consuming the optimal combination of pizza and yogurt.
The answer is TRUE
Since Sue obtains 20 utils form consuming pizza and spends $10, her utility per dollar obtained from consuming pizza = 20 / $10 = 2 util per dollar.
Since Sue obtains 40 utils form consuming yogurt and spends $20, her utility per dollar obtained from consuming yogurt = 40 / $20 = 2 util per dollar.
Since she obtains the same number of utils per dollar from pizzas and yogurt, then she is consuming the optimal combination.