The fifth term of an Arithmetic Progression is 20 and the twelfth term is 48. What is the common difference?
Answer & explanation
Correct answer: option 1
The correct answer is Option (1) → 4
In an arithmetic progression each term is the one before it plus the common difference \(d\), so \(a_n=a+(n-1)d\). Going from the 5th term to the 12th term, \(d\) is added 7 times, so the gap between the two terms is \(7d\), and the first term is not needed.
Gap between the 12th and the 5th terms: \(a_{12}-a_5=7d\)
With the given terms: \(48-20=28\), so \(7d=28\)
The common difference is \(d=4\)