From the $13$ spades in a deck of cards, four are selected. Find the probability that:

1. Exactly one card is a “face” card (Jack, Queen, or King).

   Answer (a):

   $\frac{_3C_1 \cdot _{10}C_3}{_{13}C_4}=\frac{360}{715}$

2. The cards form a sequence $\left(A, 2, 3, 4; 2, 3, 4, 5; …; J,Q, K, A\right)$.

   Answer (b):

   $≈ 0.015$