Let p + q = 10, where p, q are integers. Value-I = Maximum value of p × q when p, q are positive integers.
Quantitative Aptitude ·Previously asked in UPSC Civil Services Examination 2025
View the full solved paper: GS Paper II
Question
Let p + q = 10, where p, q are integers.
Value-I = Maximum value of p × q when p, q are positive integers.
Value-II = Maximum value of p × q when p ≥ −6, q ≥ −4.
Which one of the following is correct?
- A. Value-I < Value-II
- B. Value-II < Value-I
- C. Value-I = Value-II (Correct answer)
- D. Cannot be determined due to insufficient data
Correct Answer
Option C — Value-I = Value-II
Detailed Solution & Explanation
The correct answer is Value-I = Value-II.
Key Points
- p+q=10. Value-I: max p×q for positive integers: p=5,q=5 → 25. Value-II: max p×q for p≥−6, q≥−4, p+q=10. q = 10−p. f(p) = p(10−p).
- If p=−6: (−6)(16)=−96. If q=−4: p=14, 14×(−4)=−56. Max is still at p=5: 5×5=25. Value-I = Value-II = 25. Answer: Value-I = Value-II.