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# The sum of the first 100 positive integers is how much great

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The sum of the first 100 positive integers is how much great [#permalink]  13 Oct 2020, 06:26
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Question Stats:

99% (00:37) correct 0% (00:00) wrong based on 7 sessions
The sum of the first 100 positive integers is how much greater than the sum of the first 80 positive integers?

A. 905

B. 1,800

C. 1,805

D. 1,810

E. 1,820

Kudos for the right answer and explanation
[Reveal] Spoiler: OA

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Kudos [?]: 26 [1] , given: 1

Re: The sum of the first 100 positive integers is how much great [#permalink]  16 Oct 2020, 00:04
1
KUDOS
Quote:
The sum of the first 100 positive integers is how much greater than the sum of the first 80 positive integers?

Step 1: Understanding the question
Sum of consecutive integers = Average * number of terms
Average of consecutive integers = $$\frac{(first Term + Last Term)}{2}$$

Step 2: Calculation
sum of the first 100 positive integers = $$\frac{(1+100)}{2}$$ * 100 = 101 * 50 = 5050

sum of the first 80 positive integers = $$\frac{(1+80)}{2}$$ * 80 = 81 *40 = 3240

Difference between sum of the first 100 positive integers and sum of the first 80 positive integers = 5050 - 3240 = 1810

D is correct
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Re: The sum of the first 100 positive integers is how much great   [#permalink] 16 Oct 2020, 00:04
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