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What is the sum of (71+72+73+\cdots+100)?

Answer and explanation

Correct answer: 2565

These are 30 consecutive natural numbers from 71 to 100. Therefore, their sum is \(\frac{30}{2}(71+100)=15\times171=2565\). Hence, option B is correct. A value such as 2535 can result from an error in counting the number of terms or finding the average. Exam tip: for consecutive numbers, first count the terms using \((\text{last}-\text{first}+1)\).

Related tags

MathematicsSequences And ProgressionsNatural NumbersSum Of Consecutive IntegersArithmetic SeriesSum Of First N Natural NumbersClass 9 Mcq

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