Question

What can be placed at ‘?’ if both sides of ‘::’ have the same relationship between numbers:
85 : 42 :: 139 : ?

• A. 68
• B. 69
• C. 70
• D. 67

Hint:

In analogies where the second number is roughly half of the first, always test patterns like $(n \pm 1) / 2$ or $n / 2 \pm c$ first.

Answer 1

The Correct Option is B

Step 1: Understanding the Concept:
This problem belongs to the category of Number Analogy. We must identify the mathematical operation that transforms the first number of the pair into the second and then apply that same operation to the third number.

Step 2: Key Formula or Approach:
The relationship follows the logic: $\text{Second Number} = \frac{(\text{First Number} - 1)}{2}$.

Step 3: Detailed Explanation:
Let's analyze the first pair: \[ 85 \rightarrow (85 - 1) = 84 \] \[ 84 \div 2 = 42 \] We apply the same logic to the second part of the analogy: \[ 139 \rightarrow (139 - 1) = 138 \] \[ 138 \div 2 = 69 \]

Step 4: Final Answer:
The value that replaces the question mark is 69.