Linked percentages across variables: If 90% of A equals 30% of B and B = C% of A, find the value of C.

Difficulty: Easy

Correct Answer: 300

Explanation:


Introduction / Context:
This item connects two percentage relationships among A, B, and C. The goal is to express B as a percent of A once we compare 90% of A with 30% of B.


Given Data / Assumptions:

  • 0.90A = 0.30B.
  • B = (C/100) * A.


Concept / Approach:
Solve the first equation for B in terms of A, then equate it to (C/100) * A. Cancel A (assuming A ≠ 0), and solve for C.


Step-by-Step Solution:

From 0.90A = 0.30B ⇒ B = (0.90/0.30)A = 3A.But B is also (C/100)A.So (C/100)A = 3A ⇒ C/100 = 3 ⇒ C = 300.


Verification / Alternative check:
Check: If B = 300% of A, then 30% of B = 30% of 3A = 0.90A, which matches the left side.


Why Other Options Are Wrong:

  • 900, 800, 600 are multiples that do not satisfy both relationships simultaneously.
  • 150 would make B = 1.5A; then 30% of B would be 0.45A, not 0.90A.


Common Pitfalls:
Solving 0.90/0.30 incorrectly or forgetting that “B = C% of A” means (C/100) * A.


Final Answer:
300

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