Difficulty: Medium
Correct Answer: 2 times
Explanation:
Problem restatement
Given a current multiplicative relation and a future relation (after 8 years), determine the multiplicative factor after another 8 years.
Given data & Assumption
Concept/Approach
Use two equations to solve present ages, then compute the ratio after a further 8 years.
Step-by-step calculation
Let present ages be F (father), S (son). F = 4S F + 8 = 2.5(S + 8) 4S + 8 = 2.5S + 20 1.5S = 12 → S = 8, F = 32 After a further 8 years (i.e., after 16 years total): F + 16 = 48, S + 16 = 24 Required ratio = (F + 16)/(S + 16) = 48/24 = 2
Verification/Alternative
If “three times more” were interpreted as “three times as old” (F = 3S), then 3S + 8 = 2.5(S + 8) gives S = 24, F = 72, and after 16 years the ratio would be 88/40 = 11/5 = 2.2. Because the prompt uses “more than”, many standardized questions expect the literal 4× reading, yielding a neat integer answer 2.
Common pitfalls
Final Answer
2 times
Discussion & Comments