Question

A number series is given with one of the terms missing. Choose the correct alternative that will continue the same pattern and replace the question mark (?) in the given series. 97, 90, 76, 55, ?

• A. 28
• B. 27
• C. 26
• D. 25

Hint:

For number series, always start by checking the difference (or ratio) between consecutive numbers. If the first-level difference doesn't show a clear pattern, check the difference of the differences (second-level difference).

Answer 1

The Correct Option is B

To find the pattern in a number series, a good first step is to find the difference between consecutive terms. Step 1: Calculate the differences.
From 97 to 90: The difference is \(97 - 90 = 7\). The series is decreasing by 7.
From 90 to 76: The difference is \(90 - 76 = 14\). The series is decreasing by 14.
From 76 to 55: The difference is \(76 - 55 = 21\). The series is decreasing by 21.

Step 2: Identify the pattern in the differences. The differences are 7, 14, 21. This is a clear pattern: they are multiples of 7 in increasing order (7x1, 7x2, 7x3).

Step 3: Predict the next difference. The next difference in the pattern should be the next multiple of 7, which is \(7 \times 4 = 28\).

Step 4: Calculate the missing term in the series. The series is decreasing, so we must subtract this next difference from the last known term (55). Missing Term = 55 - 28 = 27.