R(v)= 6200 V can be used to determine the heart rate, R, of a person whose heart pumps 6200 milliliters (mL) of blood per minute and v milliliters of blood per beat. Complete parts a) through c) below. a) Find the rate of change of heart rate with respect to v, the output per beat. R'(v)= -6200 2 b) Find the heart rate at v = 90 mL per beat. The heart rate is beats/min. (Round to two decimal places as needed.) Heart rate 100 100 Output per beat 200