IBPS Clerk Prelims Model Paper 3

Concept:A proportion can be solved by cross multiplication.Explanation:Let the missing number be $x$.Then the given equation becomes $\frac{50}{x} = \frac{x}{12\frac{1}{2}}$.First change the mixed fraction: $12\frac{1}{2} = \frac{25}{2}$.So, $\frac{50}{x} = \frac{x}{\frac{25}{2}}$.Cross multiply: $50 \times \frac{25}{2} = x^2$.Simplify the left side: $25 \times 25 = 625$.Thus, $x^2 = 625$.Taking the positive square root, $x = \sqrt{625} = 25$.Verification: $\frac{50}{25}=2$ and $\frac{25}{\frac{25}{2}}=2$.So the value satisfies the equation.Answer:The missing number is $25$, which matches option D.