Find the sum of natural numbers from (126) to (175).
Answer and explanation
Correct answer: 7525
There are \(175-126+1=50\) terms from 126 to 175. Using the arithmetic progression sum formula, \(S=\frac{n}{2}(a+l)\), we get \(S=\frac{50}{2}(126+175)=25\times301=7525\). Hence, option A is correct. An answer such as 7475 can result from incorrectly counting the terms or mishandling an endpoint. Exam tip: for an inclusive range, always add \(+1\) while finding the number of terms.
Frequently asked questions
What is the correct answer to this question?
7525
Why is this the correct answer?
There are \(175-126+1=50\) terms from 126 to 175. Using the arithmetic progression sum formula, \(S=\frac{n}{2}(a+l)\), we get \(S=\frac{50}{2}(126+175)=25\times301=7525\). Hence, option A is correct. An answer such as 7475 can result from incorrectly counting the terms or mishandling an endpoint. Exam tip: for an inclusive range, always add \(+1\) while finding the number of terms.
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.
