After 15 years, a man will be just four times as old as he was 15 years ago. What is his present age?

Appeared in: OSSSC Nursing Officer-2021

Explanation

Let the present age be 'x'. The age 15 years ago was (x - 15) and the age after 15 years will be (x + 15).
The problem states that the future age is four times the past age, leading to the equation: x + 15 = 4(x - 15).
Solving the equation: x + 15 = 4x - 60, which simplifies to 3x = 75.
Therefore, x = 25. The man's current age is 25 years.

Option A: If the present age is 10, the condition '15 years ago' would result in a negative age (-5), which is not possible.
Option B: If the present age is 15, his age 15 years ago was 0. His age in 15 years will be 30. 30 is not four times 0.
Option C: If the present age is 20, his age 15 years ago was 5. His age in 15 years will be 35. 35 is not four times 5 (4 x 5 = 20).

Clinical Relevance

Nursing practice connection: This is primarily an exam-oriented knowledge point with limited direct bedside application, so retain Solving age-related word problems using linear equations as background academic context rather than a clinical decision trigger.
Aptitude and reasoning skills are tested in nursing entrance exams to assess a candidate's problem-solving abilities.
These questions evaluate logical thinking, which is a crucial skill for nurses in making quick and effective clinical decisions.
What if the question stated 'three times as old'? The equation would be x + 15 = 3(x - 15), leading to x + 15 = 3x - 45, so 2x = 60, and x = 30 years. The setup is the same, but the multiplier changes the outcome.

How to Approach the Question

First, identify the unknown quantity and assign a variable to it, such as 'x' for the present age.
Translate the word problem into mathematical expressions. '15 years ago' becomes (x - 15) and 'after 15 years' becomes (x + 15).
Set up a linear equation based on the relationship given in the problem: x + 15 = 4(x - 15).
Solve the equation for 'x' using algebraic manipulation by isolating the variable.
Finally, check your answer by plugging the value of 'x' back into the original problem statement to ensure it holds true.

Concept Tested & Keywords

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Practise the full OSSSC Nursing Officer-2021

Attempt every question from this paper in a timed mock, then review the full solution for each one.