<p>Yes, there is a curve. The ACT is scored so as to have a normal distribution, as is the SAT. Here is a chart showing which percentiles certain scores are. <a href="http://www.actstudent.org/scores/norms1.html%5B/url%5D">http://www.actstudent.org/scores/norms1.html</a>
So, a range of 27 to 30 would be the 90th to 97th percentiles of testtakers. I wouldn't be surprised if the SAT composite range reflects a similar percentile range.</p>
<p>Your practice test scores would probably be close to your actual score, give or take a little. On any given administration of the test, one's actual score will fall within a range, all else remaining equal.</p>
<p>No, it isn't generallly true that people do a lot better on the ACT. SOME do and some don't. Some do better on the SAT and some do the same on both. If you google on "ACT SAT conversion chart" you should find how scores compare. This is based on an actual study of people who took both tests and is how colleges convert scores so applicants can be compared.</p>
<p>Since both tests are curved to a normal distribution and are offered to similar populations, people can't generally do better on one or the other. In other words, only 1 percent of testtakers for either test will score at the 99th percentile, etc.</p>