Q. X said to Y, “At the time of your birth I was twice as old as you are at present.” If the present age of X is 42 years, then consider the following statements:
1. 8 years ago, the age of X was five times the age of Y.
2. After 14 years, the age of X would be two times the age of Y.
Which of the above statements is/are correct?
(a) 1 only
(b) 2 only
(c) Both 1 and 2
(d) Neither 1 nor 2
Correct Answer: (b) 2 only
Question from UPSC Prelims 2021 CSAT Paper
Explanation :
X & Y Age Relationship Analysis
Let’s say Y’s present age is y and X’s present age is 42. According to the given information, at the time of Y’s birth, X was twice as old as Y is now. So we can write the equation: 42-y = 2y. Solving for y gives us y = 14.
Now let’s check statement 1: “8 years ago, the age of X was five times the age of Y.” Eight years ago, X was 42-8 = 34 years old and Y was 14-8 = 6 years old. Since 34 is not equal to five times six (30), statement one is incorrect.
Now let’s check statement 2: “After 14 years, the age of X would be two times the age of Y.” In fourteen years’ time, X will be 42+14 =56 years old and Y will be 14+14=28 years old. Since two times twenty-eight (56) equals fifty-six (56), statement two is correct.
So only statement two is correct and therefore option (b) “2 only” is the correct answer.