If (a=11) and (a_{12}=88), what is (d)?
Answer and explanation
Correct answer: 7
The formula for an arithmetic progression is \(a_n=a+(n-1)d\). Hence, \(a_{12}=a+11d\). Substituting the given values, \(88=11+11d\), so \(11d=77\) and \(d=7\). Therefore, option C is correct. If \(d=8\), the twelfth term would be \(99\), not the given value. Exam tip: the coefficient of \(d\) in the \(n\)th term is always \(n-1\).
Frequently asked questions
What is the correct answer to this question?
7
Why is this the correct answer?
The formula for an arithmetic progression is \(a_n=a+(n-1)d\). Hence, \(a_{12}=a+11d\). Substituting the given values, \(88=11+11d\), so \(11d=77\) and \(d=7\). Therefore, option C is correct. If \(d=8\), the twelfth term would be \(99\), not the given value. Exam tip: the coefficient of \(d\) in the \(n\)th term is always \(n-1\).
Which subject and chapter does this question cover?
This is a Class 9 Mathematics question. Chapter: Sequences and Progressions. Topic: Arithmetic Progression.
Student feedback
Was this question useful?
👍 0 Helpful 👎 0 Not helpful
Yes 0% No 0%
0 responsesStudent Reviews
No published reviews yet.
