Robin says, "If Jai gives me ₹ 40, he will have half as much as Atul, but if Atul gives me ₹ 40, then the three of us will have the same amount." What is the total amount of money that Robin, Jai and Atul have between them?
Aptitude
Simplification
Difficulty: Medium
Choose an option
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A₹ 240
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B₹ 320
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C₹ 360
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D₹ 420
Answer
Correct Answer: ₹ 360
Explanation
## Concept & Logic
This requires setting up linear equations based on conditional monetary transfers. Finding a common baseline variable from the "everyone has the same amount" condition makes solving it much faster.
Let the initial amounts of Robin, Jai, and Atul be $r$, $j$, and $a$ respectively.
## Step-by-Step Solution
* **Analyze Condition 2 (The Equalizer):**
* "If Atul gives Robin ₹ 40, then the three of us will have the same amount."
* Let this final equal amount be $x$.
* Robin receives 40: $r + 40 = x \Rightarrow r = x - 40$
* Jai's amount didn't change in this scenario: $j = x$
* Atul gives 40: $a - 40 = x \Rightarrow a = x + 40$
* Now all variables are expressed in terms of $x$. The total money is $r + j + a = (x - 40) + x + (x + 40) = 3x$.
* **Analyze Condition 1:**
* "If Jai gives Robin ₹ 40, Jai will have half as much as Atul."
* Jai's new amount = $j - 40 = x - 40$
* Atul's amount remains $a = x + 40$ (in this specific conditional scenario).
* Set up the equation:
$$ x - 40 = \frac{1}{2}(x + 40) $$
$$ 2(x - 40) = x + 40 $$
$$ 2x - 80 = x + 40 $$
$$ x = 120 $$
* **Calculate Total Amount:**
* Total Amount = $3x = 3 \times 120 = 360$.
## Exam Strategy & Shortcut
Use the "same amount" clue to bypass three-variable systems. Since moving 40 from Atul to Robin equalizes everyone without involving Jai, it immediately tells you Jai is already holding the average amount ($x$).
Total money is always $3 \times \text{Average}$, so Total = $3 \times \text{Jai}$.
From the first statement: $(\text{Jai} - 40) = \frac{1}{2}(\text{Jai} + 40)$ because Atul must be $\text{Jai} + 40$ to reach the average when he loses 40.
Solving gives $\text{Jai} = 120$. Total = $360$.
## Common Pitfall
Creating three separate variables $r$, $j$, $a$ and trying to solve a messy $3 \times 3$ system of equations via substitution. This eats up valuable time and increases calculation errors. Always look for a pivot variable (like Jai in this case) to unify the terms.
## Final Answer
Therefore, the correct answer is **₹ 360**.