A research team records the systolic blood pressure (in units of millimeters of mercury) and resting heart rates (in units of beats per minute) of eight marathon runners. The blood pressures are $118$, $122$, $120$, $116$, $124$, $119$, $121$, and $117$. The heart rates are $58$, $62$, $60$, $56$, $64$, $59$, $61$, and $57$. Calculate the coefficient of variation for both blood pressure and heart rate. Which measurement is more variable relative to its mean?

• A. Blood pressure: $2.23\%$Heart rate: $4.48\%$Blood pressure is more variable
• B. Blood pressure: $2.23\%$Heart rate: $4.48\%$Heart rate is more variable
• C. Blood pressure: $2.09\%$ Heart rate: $4.19\%$ Both have the same variability
• D. Blood pressure: $4.48\%$Heart rate: $2.23\%$Heart rate is more variable

Answer: (B)