How much is the sum of natural numbers from (101) to (120)?
Answer and explanation
Correct answer: 2210
There are 20 numbers from 101 to 120, inclusive. Therefore, using the sum of an arithmetic progression,
\(S=\frac{20}{2}(101+120)=10\times221=2210\). Hence, option B is correct. The value 2190 is the sum from 100 to 119, so it does not match the given range. Exam tip: Count terms in an inclusive range using \(\text{last term}-\text{first term}+1\).
Frequently asked questions
What is the correct answer to this question?
2210
Why is this the correct answer?
There are 20 numbers from 101 to 120, inclusive. Therefore, using the sum of an arithmetic progression,
\(S=\frac{20}{2}(101+120)=10\times221=2210\). Hence, option B is correct. The value 2190 is the sum from 100 to 119, so it does not match the given range. Exam tip: Count terms in an inclusive range using \(\text{last term}-\text{first term}+1\).
Which subject and chapter does this question cover?
This is a Class 9 Mathematics question. Chapter: Sequences and Progressions. Topic: Sum of first n natural numbers.
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