Math Problem Help

<p>I took a mock test through Kaplan yesterday, and encountered this problem which I was unable to solve in the math sections. Can anyone explain how to do it/the correct response?</p>

<p>It was in a math section, appeared as #8, and #9-18 were grid-ins.</p>

<p>8) How many four-digit integers greater than zero have 3 or 6 as their third digit and 3 as their first digit?</p>

<p>(A) 144
(B) 180
(C) 200
(D) 300
(E) 720</p>

<p>Thanks!</p>

<p>Set up the four digits: ___ ___ ___ ___.</p>

<p>You have one option for the first digit (3): 1 ___ ___ ___</p>

<p>You have two options for the third digit (3 and 6): 1 ___ 2 ___</p>

<p>You have 10 options for the second and fourth digits (0, 1, 2, 3, 4, 5, 6, 7, 8, 9):<br>
1 10 2 10</p>

<p>Multiple: 1 x 10 x 2 x 10 = 200</p>

<p>SATwriter, do you actually write SAT questions?</p>

<p>@SATwriter</p>

<p>Where did you get “1 x 10 x 2 x 10” from to arrive at the answer of 200?</p>

<p>I don’t write real test questions, but I’ve simulated thousands based on those real ones (but I’d still tell you the best practice is in the Blue Book). I work for a test prep company and write courses and books. And somehow have started spending my off days talking about the SAT! </p>

<p>I got the 1 x 10 x 2 x 10 from the number of possibilities for each digit. The first digit has one possibility (a 3), so that is where the 1 comes from. The second digit has 10 possibilities (0-9), so that is where the first 10 comes from. The third digit has 2 possibilities (3 or 6) so that is where the 2 comes from. The last digit has 10 possibilities (0-9) so that is where the second 10 comes from. Multiply the possibilities together (1 x 10 x 2 x 10) to get the total number of possible combinations.</p>

<p>^ That’s neat! What does one have to do to write questions for the actual test?</p>

<p>Also, what’s your opinion on ACT? I’m from a region where most people concentrate their focus on the ACT, so will only submitting the ACT (my SAT score isn’t as good) look bad?</p>

<p>To write real test questions, you have to get a masters or PhD in psychometrics, the study of assessment. I’ve thought about it, but there are only a few schools who offer those programs. </p>

<p>As for the ACT, I think it’s fine to only submit one test as long as the admissions department states that they will take either one. I only submitted an ACT back when I applied many moons ago. Good luck!</p>