27. 28. 29. 30. The base, b, of a rectangle is inreasing at a rate of 3 in/min while the height, h, is dereasing at a rate of 3 in/min, which of the following is true about the area of the rectangle? A. A is always decreasing B. A is always increasing C. A is decreasing when b h E. A remains constant A railroad track and a road cross at right angles. An observer stands on the road 70m south of the crossing and watches an eastbound train travelling at 60m/s. At how many m/s is the train travelling away from the observer 4 seconds after it passes through the intersection? A. 57.60 B. 57.88 C. 59.20 D. 60.00 E. 67.40 In the triangle shown below, if 0 increases at a constant rate of 3 radians per minute, at what rate is x increasing in units per minute when x = 3 units? A. 3 B. 15/4 C. 4 D. 9 E. 12 The height, h, in metres, of an object at time t is given by Mr) = 8!2 -% t3 . What is the height of the object at the instant when it reaches its maximum upward velocity? A. 32 m C. 85.3 m E. O m B. 170.7 m D. 4 m