Find a vector function, r(t), that represents the curve of intersection of the two surfaces. The cylinder x2 + y2 = 81 and the surface z = xy

Atest consists of 10 multiple choice questions, each with 5 possible answers, one of which is correct. to pass the test a student must get 60% or better on the test. if a student randomly guesses, what is the probability that the student will pass the test?