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Question

When 38 is added to $30\%$ of a number. The result is 50. What is the number?

This question was previously asked in
RRB NTPC 2019 CBT 1 Question Paper (8-Mar-2021) (Shift 2)
The correct answer is
40

Finding the Unknown Number

This problem requires us to find a specific number based on a given condition involving percentages and addition.

Let the unknown number be represented by the variable x.

Setting Up the Equation

The question states that when 38 is added to 30% of a number, the result is 50. We can translate this into a mathematical equation:

$ 38 + (30\% \times x) = 50 $

To work with the percentage, we convert it to a decimal:

$ 30\% = \frac{30}{100} = 0.30 $

So the equation becomes:

$ 38 + 0.30x = 50 $

Solving the Equation Step-by-Step

  1. Isolate the term containing the variable x. Subtract 38 from both sides of the equation:

    $ 0.30x = 50 - 38 $

    $ 0.30x = 12 $

  2. Solve for x. Divide both sides by 0.30:

    $ x = \frac{12}{0.30} $

  3. Calculate the final value:

    $ x = 40 $

Conclusion

The number is 40. We can check this: 30% of 40 is $0.30 \times 40 = 12$. Adding 38 to this gives $38 + 12 = 50$, which matches the condition given in the question.

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