Some questions may have more than one correct answer.

. Let C (t) be the concentration of a drug in the bloodstream. As the body eliminates the drug, C(t) decreases at a rate that is proportional to the amount of the drug that is present at the time. Assume C(O) = 70 mg/litre (the concentration of the drug in the bloodstream at time t = 0). If the body eliminates half the drug in 30 hours, how long does it take to eliminate 90% of the drug? (2 marks) a. 20 hours b. 40 hours c. 60 hours (1. 80 hours e. 100 hours . An object with mass m is dropped from rest. We assume that air resistance is proportional to the speed of the object. If 3(t) is the distance the object falls after t seconds, then 11 = s'(t) is its velocity and a = 12' (t) is its acceleration. If g is the acceleration due to gravity, then the downward force on the object is my 01) where c is a positive constant. N ewton's Second law gives Which of the following statements are true? (2 marks) a. 11(0) = 0 C. v(t) = m(1 e? C (1. lim v(t) = 00 t>oo e. lim 12(t) = % tmo C . Let y = f (r) be a solution to the differential equation 31' = y3-lx. Which of the following statements are true? (2 marks) a. Assume that f(0) b. Assume that f(0) 0. Assume that f(0) (1. Assume that f(0) e. Assume that f(0) = 0. Then f is decreasing on [1,0]. 0. Then |f(5) f(4)| > 4. 0. Then |f(5) f(4)|