Moderate -0.5 This is a straightforward two-equation problem using standard AP formulas (nth term and sum). Students substitute given values into a₁₂ = a + 11d = 17 and S₃₁ = 31/2(2a + 30d) = 1023, solve simultaneously for a and d, then find a₃₁. While it requires algebraic manipulation, it's a routine textbook exercise with no conceptual challenges—slightly easier than average due to its mechanical nature.
3 The 12th term of an arithmetic progression is 17 and the sum of the first 31 terms is 1023. Find the 31st term.
\hfill \mbox{\textit{CAIE P1 2016 Q3 [5]}}