What is the sum of the first (6) terms of the AP (19,29,39,\ldots)?
Answer and explanation
Correct answer: 264
In this AP, the first term is \(a=19\), the common difference is \(d=10\), and \(n=6\). The sixth term is \(a_6=19+(6-1)\times10=69\). Thus, \(S_6=\frac{6}{2}(19+69)=3\times88=264\). Therefore, 264 is correct. An answer such as 254 can result from an error in finding the last term or multiplying. Exam tip: check the last term before substituting it in the sum formula.
Frequently asked questions
What is the correct answer to this question?
264
Why is this the correct answer?
In this AP, the first term is \(a=19\), the common difference is \(d=10\), and \(n=6\). The sixth term is \(a_6=19+(6-1)\times10=69\). Thus, \(S_6=\frac{6}{2}(19+69)=3\times88=264\). Therefore, 264 is correct. An answer such as 254 can result from an error in finding the last term or multiplying. Exam tip: check the last term before substituting it in the 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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