What is the sum of the first (10) terms of the AP (17,22,27,\ldots)?
Answer and explanation
Correct answer: 395
Here, the first term is \(a=17\), the common difference is \(d=22-17=5\), and \(n=10\). Using \(S_n=\frac{n}{2}[2a+(n-1)d]\), we get \(S_{10}=\frac{10}{2}[2(17)+9(5)]=5(79)=395\). Therefore, option C is correct. An answer such as 390 usually results from an error in finding the 10th term or the common difference. Exam tip: Remember to use \(n-1\) in the AP sum formula.
Frequently asked questions
What is the correct answer to this question?
395
Why is this the correct answer?
Here, the first term is \(a=17\), the common difference is \(d=22-17=5\), and \(n=10\). Using \(S_n=\frac{n}{2}[2a+(n-1)d]\), we get \(S_{10}=\frac{10}{2}[2(17)+9(5)]=5(79)=395\). Therefore, option C is correct. An answer such as 390 usually results from an error in finding the 10th term or the common difference. Exam tip: Remember to use \(n-1\) in the AP sum formula.
Which subject and chapter does this question cover?
This is a Class 10 Mathematics question. Chapter: Arithmetic Progressions (AP). Topic: Finding the sum of the first $n$ terms of an AP.
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