Answer: 5.
- A 3
- B 5
- C 10
- D 15/2
Correct answer: B. 5
Explanation: a/(1−r) = 15 and a²/(1−r²) = 45. Dividing, a/(1+r) = 3. With a = 15(1−r) this gives r = 2/3 and a = 5.
Bar heights for AP 2, 5, 8, 11 with the common difference d=3 marked between consecutive terms.
Concept context
Arithmetic progressions, geometric progressions, and sums