In an AP, (a_{17}=a_7+60) and (a_7=33). What is (a_{43})?
Answer and explanation
Correct answer: 249
In an AP, \(a_{17}-a_7=(17-7)d=10d\). Hence, \(10d=60\), so \(d=6\). Now, \(a_{43}=a_7+(43-7)d=33+36\times6=249\). Therefore, 249 is correct. Getting 255 would result from an incorrect term gap or common difference. Exam tip: the number of common differences between two terms equals the difference between their subscripts.
Frequently asked questions
What is the correct answer to this question?
249
Why is this the correct answer?
In an AP, \(a_{17}-a_7=(17-7)d=10d\). Hence, \(10d=60\), so \(d=6\). Now, \(a_{43}=a_7+(43-7)d=33+36\times6=249\). Therefore, 249 is correct. Getting 255 would result from an incorrect term gap or common difference. Exam tip: the number of common differences between two terms equals the difference between their subscripts.
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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