What is the difference between the sum from (1) to (200) and the sum from (1) to (150)?
Answer and explanation
Correct answer: 8775
Subtracting the sum from 1 to 150 from the sum from 1 to 200 leaves only the terms from 151 to 200. Thus, \(S_{200}-S_{150}=\frac{200\times201}{2}-\frac{150\times151}{2}=20100-11325=8775\). Therefore, option B is correct. A value such as 8825 can result from an arithmetic error in the addition or subtraction. Exam tip: recognise such a difference directly as the sum of the remaining consecutive terms, from 151 to 200.
Frequently asked questions
What is the correct answer to this question?
8775
Why is this the correct answer?
Subtracting the sum from 1 to 150 from the sum from 1 to 200 leaves only the terms from 151 to 200. Thus, \(S_{200}-S_{150}=\frac{200\times201}{2}-\frac{150\times151}{2}=20100-11325=8775\). Therefore, option B is correct. A value such as 8825 can result from an arithmetic error in the addition or subtraction. Exam tip: recognise such a difference directly as the sum of the remaining consecutive terms, from 151 to 200.
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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