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Question

Two numbers are, respectively, 28% and 25% less than a third number. What percent is the first number of the second number?

The correct answer is

96%

Understanding the Percentage Problem with Three Numbers

This problem involves comparing two numbers to a third number using percentages and then finding the relationship between the first two numbers as a percentage.

We are given that:

  • The first number is 28% less than a third number.
  • The second number is 25% less than the same third number.
  • We need to find what percentage the first number is of the second number.

Setting up the Calculation for Number Comparison

Let's assume the third number is \(100\). This makes calculating percentages easier.

  • Calculating the First Number:
    The first number is 28% less than the third number (\(100\)).
    Decrease = 28% of \(100 = \frac{28}{100} \times 100 = 28\).
    First Number = Third Number - Decrease = \(100 - 28 = 72\).
  • Calculating the Second Number:
    The second number is 25% less than the third number (\(100\)).
    Decrease = 25% of \(100 = \frac{25}{100} \times 100 = 25\).
    Second Number = Third Number - Decrease = \(100 - 25 = 75\).

Now we have:

Third Number 100
First Number 72
Second Number 75

Calculating What Percent the First Number is of the Second

The question asks: "What percent is the first number of the second number?"

This can be written as the formula:

$$ \text{Percentage} = \left( \frac{\text{First Number}}{\text{Second Number}} \right) \times 100\% $$

Substitute the values we found:

$$ \text{Percentage} = \left( \frac{72}{75} \right) \times 100\% $$

Step-by-Step Solution

Now, let's simplify the fraction and perform the calculation:

  1. We have the ratio \( \frac{72}{75} \).
  2. Both 72 and 75 are divisible by 3.
    \( 72 \div 3 = 24 \)
    \( 75 \div 3 = 25 \)
    So, the fraction simplifies to \( \frac{24}{25} \).
  3. Now, multiply the simplified fraction by 100% to get the percentage:
    \( \frac{24}{25} \times 100\% \)
  4. Calculate \( \frac{100}{25} = 4 \).
  5. Multiply the result by 24:
    \( 24 \times 4\% = 96\% \)

So, the first number is 96% of the second number.

Conclusion

By first determining the values of the first and second numbers relative to a chosen third number (like 100) and then calculating the ratio of the first number to the second number as a percentage, we find the required value.

Revision Table: Key Concepts Reviewed

Concept Description
Percentage Decrease Original Value - (Percentage / 100) * Original Value
Percentage of Another Number (Value 1 / Value 2) * 100%
Assuming Base Value Using 100 as a base for the third number simplifies percentage calculations.

Additional Information: Percentage Applications

Percentage is a fundamental concept used widely in various fields including finance, statistics, and everyday calculations. Understanding how to calculate percentage increase, decrease, and percentage of a quantity is crucial for solving many quantitative problems.

  • Finding "X% of Y" means \( \frac{X}{100} \times Y \).
  • Finding "What percent is X of Y" means \( \left( \frac{X}{Y} \right) \times 100\% \).
  • "X% less than Y" means \( Y - \left( \frac{X}{100} \times Y \right) \) or \( Y \left( 1 - \frac{X}{100} \right) \).
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Important Questions from Numerical Reasoning

  1. Among 150 faculty members in an institute, 55 are connected with each other through Facebook and 85 are connected through WhatsApp. 30 faculty members do not have Facebook or WhatsApp accounts. The number of faculty members connected only through Facebook accounts is ______________.

  2. X is 1 km northeast of Y. Y is 1 km southeast of Z. W is 1 km west of Z. P is 1 km south of W. Q is 1 km east of P. What is the distance between X and Q in km?

  3. A dealer sold three-forth (3/4th) of his articles at a gain of 20% and the remaining articles at the cost price. Find the gain earned by him in the whole transaction.

  4. 78, 65, 82, 69, 86, ?

  5. A traveller to the town reaches a crossroad. Upon asking residents A, B and C for directions to a certain destination, he gets the following responses

    A: turn left

    B: do not turn left

    C: go straight

    If only one among A, B and C is truthful, the traveller 

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