If the first (4) terms of an arithmetic progression are (6,13,20,27), what is (S_4)?
Answer and explanation
Correct answer: 66
Here, \(S_4\) denotes the sum of the first four terms: \(S_4=6+13+20+27=66\). Therefore, the correct answer is 66. A value such as 70 can result from misreading the last term or making an addition error. Exam tip: for a small number of terms, add directly; alternatively, use \(S_n=\frac{n}{2}[2a+(n-1)d]\).
Frequently asked questions
What is the correct answer to this question?
66
Why is this the correct answer?
Here, \(S_4\) denotes the sum of the first four terms: \(S_4=6+13+20+27=66\). Therefore, the correct answer is 66. A value such as 70 can result from misreading the last term or making an addition error. Exam tip: for a small number of terms, add directly; alternatively, use \(S_n=\frac{n}{2}[2a+(n-1)d]\).
Which subject and chapter does this question cover?
This is a Class 9 Mathematics question. Chapter: Sequences and Progressions. Topic: Arithmetic Progression.
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