Explanation:
43. P, U
44. 7
53. Airplanes can be traveling on different planes, one plane above the other. Cars on the same intersection are on the same plane.
55
a. You can choose (4 * 3 * 2)/(3 * 2) = 4 groups of 3 points in which order does not matter.
One of those combinations does not have K, so 3 combinations of the 4 have K.
p = 3/4
b. p = 1 since any three points are always coplanar.