A father is 4 times the age of his son. In 20 years, he will be twice the age of his son. What is the son's age?
Correct answer: A. 10
- A. 10
- B. 15
- C. 20
- D. 25
Explanation
To solve this, let's denote the son's current age as 'x'. According to the problem, the father's age is 4 times the son's age, so the father's age is 4x. In 20 years, the son's age will be 'x + 20' and the father's age will be '4x + 20'. The problem states that in 20 years, the father's age will be twice the son's age, so we set up the equation: 4x + 20 = 2(x + 20). Solving this equation, we get 4x + 20 = 2x + 40, which simplifies to 2x = 20, and thus x = 10. Therefore, the son is currently 10 years old. The other options do not satisfy this condition when worked through the same logic.
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Logical problems present several conditions about people, objects, events or choices and require their possible arrangements to be tested. They cover constraint-based reasoning, rankings, matching, grouping, scheduling and elimination, with attention to the difference between a complete solution and a possibility that merely satisfies one condition.
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