Raymond B. answered • 03/19/22
Math, microeconomics or criminal justice
You took a test with 28 questions.
you got 8 right and 20 wrong
your test score is number right minus number wrong
= 8 + -20 = 8-20 = -12
You failed, if 60% of 28 is passing, less is failing. You needed .6(28) = 16.8 or 17 correct to pass. You got only 8 correct.
but some tests discourage guessing so even though you got 8 right and would have had 8/28 = 28.6% as your final test grade, you also missed 20, so you end up with -12 which is in percentage terms -12/28 = -3/7
= - 42.9% which definitely brings down the average for the course. Plus getting less than zero is humiliating. If you just answered only the ones you were most certain of, you would have had a higher grade
Random guessing on a multiple choice test with 28 questions, with 4 choices for each question, would mean an expected grade of 4/28 = 1/7 or 14.3%, if there were no penalty for guessing. But with the penalty for wrong answers your expected grade would be -20/28 = -71.4% You'd do better not to guess, if you were not certain of any of the answers, and just turn in a blank answer sheet and get a 0%, which is much better than negative 71.4%. Only time guessing might be helpful is if you can with certainty eliminate 2 of the 4 choices and then feel slightly more confident that 1 of the other 2 is more likely correct.
