CA Foundation · Quantitative Aptitude · Sequence and Series
The 5th term of an AP is 23 and its common difference is 4. What is the 12th term of this AP?
The 12th term is 51. Since the 5th term is 23 and d is 4, the first term is 23 − 16 = 7. Then the 12th term equals 7 + 11×4 = 51. Alternatively, add 7 differences to the 5th term: 23 + 28 = 51.
- A51Correct
- B55
- C47
- D59
Explanation
a + 4d = 23 with d = 4 gives a = 7. The 12th term = 7 + 11×4 = 51. Choosing 55 comes from adding 12 differences to a (7 + 48), using n instead of n−1.
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