List of top Mathematics Questions on Sum of First n Terms of an AP asked in Bihar Board X

Find the sum of \(3 + 11 + 19 + \dots + 67\).
The sum of an A.P. with n terms is \(n^2 + 2n + 1\) then its 6th term is
The sum of first 20 terms of the A.P. 1, 4, 7, 10, ... is