Shortcut Trick
Let Ram's age be x. So, Mayadevi's age = 3x.
Assuming Ravi's age is x − 7 to obtain an integer value.
Soham's age = (x − 7) ÷ 4.
Given difference: 3x − (x − 7) ÷ 4 = 65 ⇒ 11x + 7 = 260 ⇒ 11x = 253 ⇒ x = 23.
Mayadevi's age = 3 × 23 = 69 years.
∴ The correct answer is 69 years.
Alternate Method
Given:
⇒ Difference between the ages of Ram and Ravi = 7 years
⇒ Mayadevi's age = 3 × Ram's age
⇒ Ravi's age = 4 × Soham's age
⇒ Difference between the ages of Mayadevi and Soham = 65 years
Calculations:
⇒ Let the age of Ram be x years.
⇒ Age of his mother, Mayadevi = 3x years.
⇒ Since Ram and Ravi differ by 7 years, let's assume Ravi's age is x − 7. (Assuming x + 7 will result in a fractional age).
⇒ Age of Ravi's brother, Soham = (x − 7) ÷ 4.
⇒ The difference between the ages of Mayadevi and Soham is 65 years:
⇒ 3x − [(x − 7) ÷ 4] = 65
⇒ (12x − x + 7) ÷ 4 = 65
⇒ 11x + 7 = 260
⇒ 11x = 253
⇒ x = 23
⇒ Therefore, Ram's age = 23 years.
⇒ Mayadevi's age = 3 × 23 = 69 years.
⇒ (Note: If we take Ravi's age as x + 7, we get 11x − 7 = 260 ⇒ x = 267 ÷ 11, which does not yield an integer value for age.)
∴ The correct answer is 69 years.
Additional Information
Linear Equations in Age Problems
Most age problems can be modeled using single-variable linear equations by expressing all ages in terms of one common person's age. Choosing the right central character minimizes complex fractional calculations.
Extraneous or Fractional Values
In quantitative aptitude, if solving an age equation yields a non-integer value where a whole number is expected, try alternating the assumed condition (e.g., swapping which person is older in an absolute difference relationship).
Constant Age Difference
The age difference between any two individuals remains constant regardless of the time elapsed, whereas the ratio of their ages changes continuously over the years.