CA Foundation · Quantitative Aptitude · Sequence and Series
Which of the following sequences is neither an arithmetic progression nor a geometric progression?
The sequence 1, 4, 9, 16 is neither an AP nor a GP. Its successive differences 3, 5, 7 are not constant and its successive ratios are not constant either. The other three sequences each have a constant difference or a constant ratio.
- A5, 10, 20, 40, ...
- B7, 5, 3, 1, ...
- C1, 4, 9, 16, ...Correct
- D3, 3, 3, 3, ...
Explanation
1, 4, 9, 16 has differences 3, 5, 7 (not constant) and ratios 4, 2.25, 1.78 (not constant), so it is neither. 5, 10, 20, 40 is a GP, 7, 5, 3, 1 is an AP, and 3, 3, 3, 3 is both an AP and a GP.
Did you get it right without looking?
One question tells you little. A timed set on Sequence and Series shows your real accuracy, how long you take and where you lose marks.
More Sequence and Series questions
- A sequence is defined by the rule t(n) = 2n² − 3n + 1. What is the sum of its 3rd and 5th terms?
- Two positive numbers a and b have AM = 10 and GM = 8. Which of the following is the value of the HM, and what is the correct relationship be…
- The sum to infinity of a GP is 12 and its first term is 3. What is the second term of the GP?
- How many terms of the AP 5, 9, 13, 17, ... must be added to get a sum of 275?
- If the sum of the first n terms of an AP is 3n² + 5n, which of the following is the common difference and the 15th term respectively?
- Two positive numbers a and b have AM = 10 and HM = 6.4. What is the absolute difference between the two numbers?