jk2010 wrote:Would someone please provide a concise breakdown of this problem. I am having a hard time understanding. Based on the question stem I don't get any of the answers, nor do I follow the explanations listed here or especially in the back of the OG.
My process.... N= 100 ----- (300-100)/2
100(100+1) = 10100/2 = 5050
The question asks for the sum of the even integers from 100 to 300, inclusive.
Ignore the formula given. Instead, use the following:
Sum = (number of integers) * (average of biggest and smallest)
To count the number of evenly spaced integers in a set:
Number of integers = (Biggest - Smallest)/(distance between each successive pair) + 1
Since we're adding only the even integers, the distance between each successive pair is 2.
Thus, the number of even integers from 100 to 300 = (300-100)/2 + 1 = 101.
Average of biggest and smallest = (300+100)/2 = 200.
Sum = (number of integers) * (average of biggest and smallest) = 101*200 = 20,200.
The correct answer is
B.
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