Infinite geometric series: a/(1 − r)

CAT has tested this idea 5 times across 5 papers, from 2017 to 2025. Solve one, and the others are the same method with different numbers or wording, which is why repeated concepts are the most efficient thing to practise.

Question	What it asks	Answer
CAT 2024 Slot 2 · QA Q8	split into two GPs with ratios 1/25 and 1/35	A
CAT 2017 Slot 2 · QA Q33	each term three times the sum after it	C
CAT 2025 Slot 2 · QA Q8	three terms' sum and pairwise products known	C
CAT 2023 Slot 3 · QA Q20	partial GP sums times powers of 1/4	B
CAT 2018 Slot 1 · QA Q9	areas of nested midpoint triangles	A

Part of Progressions & Series (38 questions since 2017).