Difficulty: Easy
Correct Answer: Data is insufficient
Explanation:
Introduction / Context:This is a data sufficiency style question disguised as a percentage/ratio problem. We are asked whether the original numbers (1998) can be uniquely determined using the given ratios and percentage changes.
Given Data / Assumptions:
Concept / Approach:Compute next-year values as factors of k and check the X : Z ratio. If the ratio condition holds identically (for all k), then k is not determined and original totals cannot be uniquely fixed.
Step-by-Step Solution:
Next year X = 3k * 1.20 = 3.6kNext year Z = 6k * 1.20 = 7.2kTheir ratio = 3.6k : 7.2k = 1 : 2 (since both sides divide by 3.6k)The ratio holds for any k, so k is not pinned down.Verification / Alternative check:Even if Y’s growth is included, it doesn’t affect the X : Z ratio. Without an absolute count or another independent equation, 1998 totals are undetermined.
Why Other Options Are Wrong:Numerical totals (5000, 6000, 75000, 7000) cannot be justified uniquely from the data.
Common Pitfalls:Assuming ratios alone can produce exact totals; missing that a free scale factor k remains.
Final Answer:Data is insufficient
Discussion & Comments