<p>It's #36 on pg 201 in the CB's general Subject Test book. I'm looking for some help; I just can't come up with the answer.</p>
<p>The only prime factors of a number n are 2, 5, 7, and 17. Which of the following could NOT be a factor of n?</p>
<p>a) 10
b) 20
c) 25
d) 30
e) 34</p>
<p>Thanks...</p>
<p>30.</p>
<p>because that means 3 is also a factor, and 3 is a prime number.</p>
<p>10: 2, 5
20: 2, 4, 5, 10
25: 5
30: 2, 3, 5, 6, 10, 15
34: 2, 17</p>
<p>So the answer would be D, since 3 is a prime number but not listed as a factor of n.</p>
<p>Tell me if I'm right - is it D?</p>
<p>LOL guess I am :D. Didn't see the earlier posts :).</p>
<p>thank you...it's d on the solution sheet :)</p>