Question

Alcohol costs Rs.\ 3.50 per litre and kerosene oil costs Rs.\ 2.50 per litre. In what proportion should these be mixed so that the resulting mixture may be Rs.\ 2.75 per litre?

• A. \(1:2\)
• B. \(1:4\)
• C. \(1:5\)
• D. \(1:3\)
• E. \(1:1\)

Answer 1

The Correct Option is D

Concept:
Use
Alligation Rule:
\[ \text{Ratio} = \frac{\text{Difference with mean (higher)}}{\text{Difference with mean (lower)}} \]
Step 1: Apply alligation.
\[ \text{Alcohol} = 3.5,\quad \text{Kerosene} = 2.5,\quad \text{Mean} = 2.75 \] \[ \text{Ratio} = (3.5 - 2.75) : (2.75 - 2.5) \] \[ = 0.75 : 0.25 = 3 : 1 \] Thus: \[ \text{Alcohol : Kerosene} = 1 : 3 \]
Step 2: Option analysis.

• (A) 1:2: Incorrect $\times$
• (B) 1:4: Incorrect $\times$
• (C) 1:5: Incorrect $\times$
• (D) 1:3: Correct \checkmark
• (E) 1:1: Incorrect $\times$

Conclusion:
Thus, the correct answer is
Option (D).