Question

Two pairs of statements about Jeff's housing expenditures are given below. How can both pairs of statements be true?

Answer 1

Explanation:

Pair 1 is true if Jeff's monthly income is $600/20% = $3,000.

Pair 2 is true if Jeff's monthly income is $1200/10% = $12,000.

Both pairs can be true if Jeff's monthly income increased by a factor of 4 in the 20 years from 1990 to 2010.

Obviously, Jeff spent more on housing in 2010. (Fortunately for Jeff, that larger expenditure was a smaller fraction of his income.)