A cardiac monitor is used to measure the heart rate of a patient after surgery It compiles the number of heartbeats after t minutes When the data in the table are graphed the slope of the tangent line represents the heart rate in beats per minute t min 36 38 40 42 44 Heartbeats 2505 2640 2773 2906 3042 The monitor estimates this value by calculating the slope of a secant line Use the data to estimate the patient s heart rate after 42 minutes using the secant line between the points with the given values of t Round your answers to one decimal place a t 36 and t 42 67 8 x b t 38 and t 42 67 25 X c t 40 and t 42 66 5 d t 42 and t 44 69