The sum of the present ages of two sisters is 67 years. Five years ago from now, the elder sister was twice as old as the younger one. Find the elder sister's current age.
- AOption (a)
27 years
- BOption (b)
43 years
- COption (c)
40 years
- DOption (d)
24 years
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Correct answer
43 years
Why this answer is correct
Shortcut Trick
Sum of ages 5 years ago → 67 − (5 × 2) = 57 years.
Age ratio 5 years ago (Elder : Younger) = 2 :
- Elder sister's age 5 years ago = (2/3) × 57 = 38 years.
Current age of elder sister = 38 + 5 = 43 years.
∴ The correct answer is 43 years.
Alternate Method
Given: Sum of present ages = 67 years. Ratio 5 years ago = 2 :
- Formula: Age after 'n' years = Age 'n' years ago + (n × 2 for two people).
⇒ Let ages 5 years ago be 2x and x.
⇒ Present ages = (2x + 5) and (x + 5).
⇒ (2x + 5) + (x + 5) = 67
⇒ 3x + 10 = 67
⇒ 3x = 57 ⇒ x = 19.
⇒ Elder sister's current age = 2x + 5 = (2 × 19) + 5 = 38 + 5 = 43.
∴ The correct answer is 43 years.
Additional Information
Age Difference Constant
The difference between the ages of two people always remains constant, regardless of the number of years passed.
Sum of Ages Change
If there are 'n' people, the sum of their ages increases or decreases by (n × number of years).
Ratio Method
When a constant number of years is added to both parts of a ratio, the difference between ratio units should be balanced if the age difference is known.