AMC 10B 2003 Problem 6

Many television screens are rectangles that are measured by the length of their diagonals. The ratio of the horizontal length to the height in a standard television screen is 4: 3. The horizontal length of a 27 -inch television screen is closest, in inches, to which of the following?

Answer Choices
A. 20
B. 20.5
C. 21
D. 21.5
E. 22