IBPS PO Mains 12 Oct 2025 Shift 1 Paper

Concept:The race has two stages: the first 2 hours at initial speeds, then the remaining distance at changed speeds. Total time = first 2 hours + time for remaining distance.Explanation:Step 1: Find the new speeds after 2 hours.Speed of C becomes 80% of initial speed of A: $v_C = 0.80 \times 50 = 40$ km/h.Speed of A becomes 25% higher than the new speed of C: $v_A = 1.25 \times 40 = 50$ km/h.Speed of B becomes 10% higher than its initial speed: $v_B = 1.10 \times 40 = 44$ km/h.Step 2: Calculate distance covered in the first 2 hours and the remaining distance.Bike A: $50 \times 2 = 100$ km covered; remaining $= 300 - 100 = 200$ km.Bike B: $40 \times 2 = 80$ km covered; remaining $= 300 - 80 = 220$ km.Bike C: $60 \times 2 = 120$ km covered; remaining $= 300 - 120 = 180$ km.Step 3: Calculate the total time for each bike.Total time of A: $2 + \frac{200}{50} = 2 + 4 = 6$ hours.Total time of B: $2 + \frac{220}{44} = 2 + 5 = 7$ hours.Total time of C: $2 + \frac{180}{40} = 2 + 4.5 = 6.5$ hours.Step 4: Identify the 1st and 2nd position bikes and find the difference.Bike A finishes 1st in 6 hours, and bike C finishes 2nd in 6.5 hours.Difference $= 6.5 - 6 = 0.5$ hours $= 0.5 \times 60 = 30$ minutes.Answer:The required difference in time is 30 minutes, i.e., Option D.