9. A cardiac monitor is used to measure the heart rate of a patient after surgery and to compute the total number of heartbeats after / minutes. When the data are graphed, the slope of the tangent line represents the heart rate, in beats per minute. t (min) 36 38 40 42 44 Heartbeats 2530 2661 2806 2948 3080 The monitor estimates this value by calculating the slope of a secant line. Use the data in the table to find the slope of the secant line between the points with the given values of t. (a t = 36 and t = 42 (b t = 38 and t = 42 (c t = 40 and t = 42 (d) t = 42 and t = 44