Problem: The percent that x is less than y is
Answer Choices:
A. x100(y−x)
B. x100(x−y)
C. y100(y−x)
D. 100(y−x)
E. 100(x−y)
Solution:
y−x is the excess of y over x. The basis of comparison is the ratio of the excess to y, namely, (y−x)/y. Therefore, the per cent required is 100(y−x)/y.