PWN the SAT Math Guide p. 112 (p. 110 in later printing) #3:

Question relating to the exponent in the answer: It is a little unclear to me that the Value column indicates the value at the END of each year. The text states that the values represent “the value of his account in each of the next three years.” Must we presume that “in each” means at the END of each of those years, at which point the interest would have been accrued for that full year?

Your question is a good one—I think I could have been a bit more careful with the wording on this one and I will tighten that up in the 5th edition. The key to getting this, though, is looking at the table and the answer choices. The answer choices show you that your starting value must be 3000 and that you’re either increasing by 10% per year (choices A and B), 1% per year (choice C), or -90% per year (choice D). Obviously choice D is right out, and a quick look at the year 1 and year 2 values (3000 to 3300) shows that 10% is what you’re looking for.

From there, you need to figure out whether year 7 will be 3000(1.1)^6 or 3000(1.1)^7. The way I’d recommend thinking about this is looking, again, at the first two values. The year 1 value is 3,000, which suggests that the exponent in year 1 is zero (i.e., 3000(1.1)^0=3000). Likewise, the exponent in year 2 should be 1 (i.e., 3000(1.1)^1=3300). Following that pattern suggests that the exponent in year 7 should be 6. Does that help?