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The income of Amala is 20%20 \% more than that of Bimala and 20%20 \% less than that of Kamala. If Kamala's income goes down by 4%4 \% and Bimala's goes up by 10%10 \%, then the percentage by which Kamala's income would exceed Bimala's is nearest to

Solution

✅ Correct Option: 3

We need to find how much more Kamala earns compared to Bimala after both their incomes change. We'll work with the relationships given systematically.


We assume Bimala's income = Rs. 100

When dealing with percentage problems, assuming one value as 100 makes calculations much easier. Since we're looking for percentage differences, the actual amounts don't matter - only the ratios between them.


Amala earns 20% more than Bimala

Amala's income = 100 + 20% of 100 = 100 + 20 = Rs. 120

Amala earns 20% less than Kamala

This means: Amala = Kamala - 20% of Kamala = 0.80 × Kamala

So: 120 = 0.80 × Kamala

Therefore: Kamala = 120 ÷ 0.80 = Rs. 150

Quick Check: 20% of 150 = 30, so 150 - 30 = 120


Bimala's income goes up by 10%

New income = 100 + 10% of 100 = 100 + 10 = Rs. 110

Kamala's income goes down by 4%

New income = 150 - 4% of 150 = 150 - 6 = Rs. 144


When we want to find by what percentage A exceeds B:

Percentage=A - BB×100\text{Percentage} = \dfrac{\text{A - B}}{\text{B}} \times 100

Required percentage=144−110110×100\text{Required percentage} = \dfrac{144 - 110}{110} \times 100

=34110×100= \dfrac{34}{110} \times 100

=3411×10=30.9%= \dfrac{34}{11} \times 10 = 30.9\%

Since the question asks for the nearest percentage, 31% is our answer.


When solving percentage comparison problems:

  1. Assume convenient values (like 100) for easier calculation
  2. Work step-by-step through each relationship
  3. Always verify your intermediate results
  4. Use the standard formula for percentage excess: DifferenceBase×100\dfrac{\text{Difference}}{\text{Base}} \times 100

Answer: 31%

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