If integer k is equal to the sum of all even multiples of 25 between 200 and 600, what is the greatest prime factor of k? Answers:	A) 5	B) 7	C) 11	D) 13	E) 17
if we break down what the stem is asking what is the sum of all mult of 50 between 200 and 600.   using arithmetic progression to find n : 600 = 200 + (n - 1) 50   400+ 50 = 50n   450 = 50n =&gt; n = 9   the sum would be: 9* mean   mean = [600 + 200] / 2 = 400   9*400= 
<gadget id="calculator">9*400</gadget>
<output>3_600</output>
3600   13
<result>D</result>
If integer k is equal to the sum of all even multiples of 25 between 200 and 600, what is the greatest prime factor of k?