In each of the following series, determine the pattern and find the missing number represented by (?). Choose the correct answer from the given options.
80, 95, 75, 90, 70, (?)
Show answer & explanation
Correct answer: B
Explanation
The given number series follows an alternating pattern of addition and subtraction:
• 80 + 15 = 95
• 95 − 20 = 75
• 75 + 15 = 90
• 90 − 20 = 70
• 70 + 15 = 85
Alternatively, looking at alternate terms:
• Odd places: 80, 75, 70 (−5 each step)
• Even places: 95, 90, 85 (−5 each step)
Therefore, the missing number is 85.