Let's analyze each option to determine which one accurately describes what it means to get 80% on a test.
1. The test had 80 problems on it and you got all of them correct.
- If you got all 80 problems correct, that would be 100%, not 80%. This option is incorrect.
2. The test would have to have 100 questions for you to be able to get 80% on it.
- Having 100 questions and getting 80% would mean answering 80 questions correctly. However, 80% can be achieved on any number of questions as long as 80% of them are correct. This option is misleading and incorrect.
3. If the test had 50 questions on it, you would have correctly answered 30 of the questions.
- 80% of 50 questions is calculated as follows:
[tex]\[
0.80 \times 50 = 40
\][/tex]
Therefore, if the test had 50 questions, you would have answered 40 questions correctly, not 30. This option is incorrect.
4. If the test had 100 questions, you incorrectly answered 20 of them.
- 80% of 100 questions would imply that 80 questions were answered correctly. Therefore, 100 - 80 = 20 questions would be answered incorrectly. This option is correct.
Hence, the correct answer is:
If the test had 100 questions, you incorrectly answered 20 of them.
