What a forty-question test can and cannot express
A forty-question test, long enough for a full class period and common as a mid-term.
Every question on a forty-question paper is worth 2.5% of the grade, so the only grades that exist are the 40 multiples of that figure. That is fine enough to reach every letter band, though several of them start a percentage point or two above their nominal floor.
The practical consequence is that a borderline case on a forty-question test is decided by a single question. Going from 24 correct to 23 moves the grade by2.5% — the difference between 60% and 57.5%, or between a D- and an F on a 60% pass mark. 23 out of 40 is the highest score on this test that still fails.
What each letter needs out of 40
| Letter | Starts at | Lowest score out of 40 | Which is |
|---|---|---|---|
| A+ | 97% | 39 out of 40 | 97.5% |
| A | 93% | 38 out of 40 | 95% |
| A- | 90% | 36 out of 40 | 90% |
| B+ | 87% | 35 out of 40 | 87.5% |
| B | 83% | 34 out of 40 | 85% |
| B- | 80% | 32 out of 40 | 80% |
| C+ | 77% | 31 out of 40 | 77.5% |
| C | 73% | 30 out of 40 | 75% |
| C- | 70% | 28 out of 40 | 70% |
| D+ | 67% | 27 out of 40 | 67.5% |
| D | 63% | 26 out of 40 | 65% |
| D- | 60% | 24 out of 40 | 60% |
Clearing the 93% A cut-off takes 38 out of 40, which allows 2 wrong answers; that score actually lands on95%, an A. A pass at 60% takes 24 out of 40, allowing 16 wrong. Those cut-offs are the common US ones and your school's may differ by a point or two — the percentage column is the part that transfers, and the letter grade to GPA page gives the full band table with grade points on the 4.0, 4.3 and 5.0 scales.
Every score out of 40
40 rows, highest first: the score, the percentage it produces, the letter it lands in on a standard plus/minus scale, and how many questions that leaves wrong. Each score links to a page working that grade out in full, including what the next letter up would take and what the same percentage looks like on a test of a different length.