Cards numbered as 12, 13, 14, . . ., 51, (one number on one card) are kept in a box and mixed thoroughly. One card is chosen at random from the box. What is the probability that the number on the chosen card is a composite number between 21 and 42 ?
1
\(\frac{1}{2} \)
2
\(\frac{7}{20} \)
3
\(\frac{3}{8} \)
4
\(\frac{17}{40}\)