IBPS PO Mains 12 Oct 2025 Shift 1 Paper

Concept:Find the missing terms $P$, $Q$, and $R$ by identifying the pattern in each series, then compute $Q - R$.Explanation:For Series A, starting from the second term, each term is obtained by multiplying the previous term by consecutive numbers $5, 6, 7, 8$ and adding $1$.$3 \times 5 + 1 = 16$$16 \times 6 + 1 = 97$$97 \times 7 + 1 = 680$$680 \times 8 + 1 = 5441$Hence, $P = 680$.Using $P$, the third term of Series B is:$3.5 \times 680 + 172 = 2380 + 172 = 2552$So Series B becomes: $Q$, $Q - 400$, $2552$, $2296$, $2100$, $1956$, $R$.Check the differences between known terms:$2552 - 2296 = 256 = 16^2$$2296 - 2100 = 196 = 14^2$$2100 - 1956 = 144 = 12^2$The differences are squares of even numbers in descending order.So the next difference before $R$ is $10^2$:$R = 1956 - 10^2 = 1956 - 100 = 1856$For the first gap, the difference is $20^2$, and for the second gap it is $18^2$:$Q - (Q - 400) = 400 = 20^2$$Q - 400 = 2552 + 18^2 = 2552 + 324 = 2876$$Q = 2876 + 400 = 3276$Therefore:$Q - R = 3276 - 1856 = 1420$Answer:$\boxed{1420}$The correct option is B.