If an AP has (a=2.5), (d=2.5), and (n=10), what is (a_n)?
Answer and explanation
Correct answer: \(25\)
The \(n\)th term of an AP is \(a_n=a+(n-1)d\). Thus, \(a_{10}=2.5+(10-1)\times2.5=2.5+22.5=25\). Hence, the correct answer is \(25\). The value \(27.5\) would result from incorrectly using \(10d\) instead of \((10-1)d\). Exam tip: Always use \((n-1)\) in the formula for the \(n\)th term.
Frequently asked questions
What is the correct answer to this question?
\(25\)
Why is this the correct answer?
The \(n\)th term of an AP is \(a_n=a+(n-1)d\). Thus, \(a_{10}=2.5+(10-1)\times2.5=2.5+22.5=25\). Hence, the correct answer is \(25\). The value \(27.5\) would result from incorrectly using \(10d\) instead of \((10-1)d\). Exam tip: Always use \((n-1)\) in the formula for the \(n\)th term.
Which subject and chapter does this question cover?
This is a Class 10 Mathematics question. Chapter: Arithmetic Progressions (AP). Topic: Finding the $n$th term of an AP.
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