Series completion (Numbers/Letters): Look at this series: 80, 10, 70, 15, 60, ... What number should come next?
Correct answer: A. 20
- A. 20
- B. 25
- C. 30
- D. 50
Explanation
Let's analyze the given series: 80, 10, 70, 15, 60, ... In this series, there are two alternating sequences. In the first sequence, we are subtracting 10 from each number to obtain the next number: 80 - 10 = 70, 70 - 10 = 60, and so on. In the second sequence, we are adding 5 to each number to obtain the next number: 10 + 5 = 15, 15 + 5 = 20, and so on. Continuing this pattern, the next number in the series should follow the second sequence: 15+ 5 = 20. Therefore, the next number in the series should be 20.
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Series questions use numbers, letters, symbols or combinations arranged according to a hidden pattern. You may need to identify repeated operations, alternating rules, alphabetical positions, differences, reversals and mixed sequences to find a missing term or predict the next one.
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