Two numbers are such that the square of one is 224 less than 8 times the square of the other. If the numbers be in the ratio of 3 : 4, the numbers are
Aptitude
Problems on Numbers
Difficulty: Medium
Choose an option
-
A6, 8
-
B9, 12
-
C12, 16
-
DNone of these
Answer
Correct Answer: 6, 8
Explanation
## Concept & Logic
When two numbers are given as a ratio, they can be expressed using a common variable multiplier (e.g., $3x$ and $4x$). The problem translates to an algebraic equation relating their squares.
$$ (4x)^2 = 8(3x)^2 - 224 $$
## Step-by-Step Solution
* **Given:** The ratio of the numbers is $3:4$. Let the numbers be $3x$ and $4x$.
* **Calculation / Deduction:**
* Square of the first number = $(3x)^2 = 9x^2$
* Square of the second number = $(4x)^2 = 16x^2$
* According to the condition, the square of one is 224 less than 8 times the square of the other. Let's test the relation: $16x^2 = 8(9x^2) - 224$
* $16x^2 = 72x^2 - 224$
* $56x^2 = 224$
* $x^2 = 4$
* $x = 2$
* The numbers are $3(2) = 6$ and $4(2) = 8$.
## Exam Strategy & Shortcut
**Option Elimination:** Instead of solving the quadratic equation, directly test the options.
Option (a) 6 and 8: Square of 8 is 64. 8 times the square of 6 is $8 \times 36 = 288$. The difference is $288 - 64 = 224$. This matches the condition perfectly, saving you valuable time.
## Common Pitfall
Students often misinterpret "square of one is 224 less than 8 times the square of the other" and set up the equation backwards, subtracting from the wrong variable. Always use common sense or option verification to confirm the logical relationship.
## Final Answer
**Therefore, the correct answer is 6, 8.**