If x % of 80 = 20% of y, then x = ? and y = ?
Correct answer: D. Cannot be determined
- A. x = 20, y = 20
- B. x = 20, y = 40
- C. x = 20, y = 80
- D. Cannot be determined
Explanation
x% of 80 is 80x/100 = 0.8x, while 20% of y is 20y/100 = 0.2y. Thus 0.8x = 0.2y, giving y = 4x, so many pairs are possible and the exact values cannot be determined. The common trap is choosing x = 20 and y = 80, which is only one possible pair, not the unique pair.
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About Percentages
Percentages express a quantity as parts per hundred and support calculations involving increases, decreases, discounts, commissions, taxes, and successive changes. Questions require distinguishing percentage change from percentage points and identifying the original value when a final value and its percentage change are given.
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