<p>Hi all,</p>
<p>The question is the following:
[screen</a> shot](<a href=“Imgur: The magic of the Internet”>Imgur: The magic of the Internet)</p>
<p>What I did:</p>
<p>I figured that for the observer the length is smaller and given by the formula: L=L0/gamma.
–> 12.64 = L0/(1/sqrt(1-(0.85c)^2/c^2)</p>
<p>I found that L0 is 6.65m.</p>
<p>The book (Petersons SAT II success) says its D (24m).</p>
<p>Am I wrong or is it an error in the book?</p>
<p>Thanks</p>