IStock Photo 406782 © Dan Fletcher

If you are one of the millions of high school students taking the May 1st SAT, you might just be wondering (especially if you have a high grade point average, or maybe just a high opinion of yourself): what are the chances I could flat-out ace this thing?

Based on 2008 score results, the odds you will open the mail a few weeks from now and learn you have earned the top score of 2400 are 1 in 5,152. If that doesn’t sound too bad, consider this: those are about the same odds that a person age 15-44 will die from appendicitis ( 1 in 5,150). Don’t hear of that too often.

In 2008, the total number of college seniors who took the SAT was just over 1.5 million. Between 60,000 and 90,000 students scored 700 or higher (out of 800) on at least one of the sections (critical reading, mathematics, or writing), but only 297 seniors achieved the coveted 2400.

Scores in each of three topic areas (critical reading, mathematics, and writing) range from 200 to 800, making the total score range 600 to 2400. An SAT score is the number of questions answered correctly, minus a fraction of a point deducted for each multiple-choice question answered incorrectly (nothing is deducted for incorrect student-produced responses or unanswered questions). However, because results are scaled, a student can answer several questions incorrectly, and still earn a 2400—making that the top score, but not necessarily a “perfect” score.

The highest possible score on the ACT test comes with a similar caveat. An ACT score does not penalize for questions answered incorrectly or left blank. Its four sections (English, mathematics, reading, and science) are each scored on a scale from 1 to 36, and then those four numbers are averaged and rounded up to create a test-taker’s total composite score, which consequently ranges from 1 to 36.

With the ACT, it’s not just the scale, but also the averaging that gives test-takers a break. The scaling of individual tests is such that at least one question on a section may be incorrect and the section may still earn a 36. This averaging means that a total composite score of 36 is possible even with scores of 35 on two of the four tests.

The likelihood of achieving the highest score of 36 on the ACT is slightly more than double the likelihood of achieving a 2400 on the SAT, but still a very impressive accomplishment. The odds a graduating senior in 2009 that took the ACT received a top score are 1 in 2,320, which are not far from the odds a live birth to a woman 20 - 24 will be part of a triplet or higher order (think quadruplets, quintuplets!) multiple delivery: 1 in 2,400. In 2009, of the just under 1.5 million seniors who took the ACT, 638 seniors earned a perfect score, the most in the last 5 years.