The lowest is the square root of 9 which is 3. After that is 3.15, 13/4 (3.25), 3 1/2 (3.50). My explanation would be: first I found out the square root of 9. Then divided 13 by 4.
It is decreased by a factor of 3. You can determine this by realizing that one inch original equals 3.3 feet, but the equals 1.1 feet, and 3.3/1.1 = 3.
