Alexandra has determined that studying an hour for her economics quiz will improve her grade on the quiz from 75 to 100. She also determines that this improvement is worth $20. To study for an hour for her economics quiz, however, she will have to work one fewer hour at her part-time job. Alexandra should:

study when the hourly rate is below or equal to $20

Explanation:

Cosidering the economic principles of opportnity cost Alexandra will only study that extra time if the loss wages are less or equal to $20 dollars

as a higher hourly  rate will make the $20 dollar she consider the change in grade worth it to leave a net loss after considering the implicit cost of the test

the answer to this question would be shared investment