In the sequence (19,31,43,55,\ldots), which term is (151)?
Answer and explanation
Correct answer: 12th
This is an arithmetic progression with first term \(a=19\) and common difference \(d=12\). Its \(n\)th term is \(a_n=a+(n-1)d\). Thus, \(19+(n-1)\times12=151\), so \((n-1)\times12=132\), giving \(n-1=11\) and \(n=12\). Hence, 151 is the 12th term. The 13th term would be 163, so it is not correct. Exam tip: while finding a term number, use \(n-1\) correctly in the AP formula.
Frequently asked questions
What is the correct answer to this question?
12th
Why is this the correct answer?
This is an arithmetic progression with first term \(a=19\) and common difference \(d=12\). Its \(n\)th term is \(a_n=a+(n-1)d\). Thus, \(19+(n-1)\times12=151\), so \((n-1)\times12=132\), giving \(n-1=11\) and \(n=12\). Hence, 151 is the 12th term. The 13th term would be 163, so it is not correct. Exam tip: while finding a term number, use \(n-1\) correctly in the AP formula.
Which subject and chapter does this question cover?
This is a Class 9 Mathematics question. Chapter: Sequences and Progressions. Topic: nth term.
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