A person \( x \) inches tall has a pulse rate of \( y \) beats per minute, as given approximately by \( y=597 x^{-1 / 3} \) for \( 30 \leq x \leq 75 \). What is the instantaneous rate of change of pulse rate for the following heights? (A) 40 -inches (B) 61 -inches What is the instantaneous rate of change of pulse rate for a 40 inch tall person? \( \square \) beats per minute per inch (Round to the nearest hundredth as needed.)
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To find the instantaneous rate of change of pulse rate with respect to height, we need to calculate the derivative of the function \( y = 597 x^{-1/3} \) with respect to \( x \). Let's differentiate: \[ \frac{dy}{dx} = 597 \cdot \left(-\frac{1}{3}\right) x^{-4/3} = -199 \cdot x^{-4/3} \] Now we can evaluate this derivative at the specified heights. **For 40 inches:** \[ \frac{dy}{dx} \bigg|_{x=40} = -199 \cdot (40)^{-4/3} \approx -199 \cdot (0.0160) \approx -3.184 \] Rounded to the nearest hundredth, the instantaneous rate of change of pulse rate for a 40-inch tall person is approximately \(-3.18\) beats per minute per inch. **For 61 inches:** \[ \frac{dy}{dx} \bigg|_{x=61} = -199 \cdot (61)^{-4/3} \approx -199 \cdot (0.0084) \approx -1.672 \] Rounded to the nearest hundredth, the instantaneous rate of change of pulse rate for a 61-inch tall person is approximately \(-1.67\) beats per minute per inch.