高階math-u01-d03
A price falls by 25% and then rises by 20%. Compared with the original price, the final price is:
A. 10% lower✓ 答案
B. unchanged
C. 5% higher
D. 20% lower
解說
Percentage changes compound by multiplying the factors: 0.75 x 1.20 = 0.90. The final price is 90% of the original, so it is 10% lower. Adding and subtracting the percentages would give a wrong answer because the bases differ.