Find the fraction (in lowest terms): If 1 is added to the denominator of a fraction, the value becomes 1/2; and if 1 is added to the numerator, the value becomes exactly 1. What is the original fraction?

Difficulty: Easy

Correct Answer: 2/3

Explanation:


Introduction / Context:
This problem asks you to determine a rational number (a fraction) from two simple transformations. When 1 is added to the denominator, the fraction equals 1/2. When 1 is added to the numerator, the fraction equals 1. Translating each verbal condition into an equation and solving the resulting system is a classic aptitude skill.


Given Data / Assumptions:

  • The fraction is x / y with x and y as positive integers and y ≠ 0.
  • Condition A: x / (y + 1) = 1/2.
  • Condition B: (x + 1) / y = 1.
  • We seek the simplest form of the fraction.


Concept / Approach:
Convert each sentence into an algebraic equation, then solve simultaneously. From Condition B, (x + 1) / y = 1 implies y = x + 1. Substitute this into Condition A to find x. Once x is known, compute y and write the fraction x / y in lowest terms.


Step-by-Step Solution:

From (x + 1) / y = 1, obtain y = x + 1.Use x / (y + 1) = 1/2. Substitute y = x + 1 to get x / (x + 2) = 1/2.Cross-multiply: 2x = x + 2, which gives x = 2.Then y = x + 1 = 3, so the original fraction is 2/3.


Verification / Alternative check:
Add 1 to the denominator: 2 / (3 + 1) = 2/4 = 1/2 (matches). Add 1 to the numerator: (2 + 1) / 3 = 3/3 = 1 (matches). Everything is consistent.


Why Other Options Are Wrong:
4/7, 5/9, 10/11, and 3/5 do not satisfy both conditions; testing either condition fails for each distractor.


Common Pitfalls:
Mixing up which operation (adding 1) applies to the numerator versus the denominator; forgetting to substitute y = x + 1 correctly; or reducing too early and losing track of variables.


Final Answer:
2/3

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