Answer: 100.
- A 80
- B 90
- C 100
- D 110
Correct answer: C. 100
Explanation: a = 1, d = 2. S10 = 10/2 [2(1) + 9(2)] = 5[2+18] = 5×20 = 100.
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