The physical fitness of a patient is often measured by the patient's maximum oxygen uptake. The mean maximum oxygen uptake for cardiac patients who regularly participate in sports or exercise programs was found to be 24.1 and with a standard deviation of 6.30. Assume that this distribution is approximately normal.
a) What is the probability that a cardiac patient who regularly participates in sports has a maximum oxygen uptake of at least 20 ml/kg?
b) What is the probability that a cardiac patient who regularly exercises has a maximum oxygen uptake of 10.5 ml/kg or lower?