Look at this series: 80, 10, 70, 15, 60, ... What number should come next?
2026
Look at this series: 80, 10, 70, 15, 60, ... What number should come next?
- A.
20
- B.
25
- C.
30
- D.
50
Attempted by 1829 students.
Show answer & explanation
Correct answer: A
Answer: 20
Explanation:
Split the sequence into two interleaved subsequences: terms in positions 1, 3, 5, ... are 80, 70, 60; terms in positions 2, 4, 6, ... are 10, 15, ...
The first subsequence decreases by 10 each time: 80 → 70 → 60.
The second subsequence increases by 5 each time: 10 → 15 → 20.
The next term in the overall sequence is the next value of the second subsequence, which is 20.