<p>Hello! Here is a SAT question from CollegeBoard: <a href="http://i56.tinypic.com/23ur3lt.jpg%5B/url%5D">http://i56.tinypic.com/23ur3lt.jpg</a></p>
<p>Can somebody please explain how to arrive at this answer?</p>
<p>Thanks in advance for helping me out.</p>
<p>…?</p>
<p>Ok…</p>
<p>Plug in 0 and call that x.
Plug in 2 and call that y. </p>
<p>X-Y= 171.95</p>
<p>About 180.</p>
<p>Wouldn’t you compute it like:</p>
<p>n(2) = 500(0.81)^2
and…
n(0) = 500(0.81)^0</p>
<p>They want to know the difference between </p>
<p>328.05 when n=2
500.0 when n=0</p>
<p>take initial and final, find the difference. Right?</p>
<p>Yup, that’s the way.</p>
<p>The trick here is the decade. Good thing it was underlined, I don’t think I would’ve noticed it otherwise.</p>
