Multiple choice

The ratio of the present ages of two individuals A and B is 1 : 4, respectively. If the ratio of their ages two years ago was 1 : 10, then B's age 3 years from now will be (in years)

  1. 12

  2. 15

  3. 18

  4. 21

  5. 24
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

Let ages be A=x, B=4x. Two years ago: (x-2)/(4x-2) = 1/10. Solving gives 10x-20 = 4x-2, so 6x=18, x=3. Present ages are A=3, B=12. B's age in 3 years will be 12+3=15.

AI explanation

Let the present ages of A and B be x and 4x respectively. Two years ago, their ages were x minus 2 and 4x minus 2, and the given ratio is 1 to 10, establishing the equation x minus 2 divided by 4x minus 2 equals 1 divided by 10. Cross multiplying yields 10x minus 20 equals 4x minus 2, which simplifies to 6x equals 18 and x equals 3. B's present age is 4 times 3, which is 12 years, so B's age 3 years from now will be 12 plus 3, resulting in 15 years.

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