Final Answer:
Holly's target heart rate at 70 percent intensity, being 30 years old, would be 154 beats per minute (bpm). Thus option B is correct.
Step-by-step explanation:
The target heart rate is calculated using the Karvonen formula, which takes into account age and exercise intensity. First, determine Holly's maximum heart rate (HRmax) using the formula: 220 - Age = HRmax.
Therefore, HRmax = 220 - 30 = 190 bpm.
Next, calculate the target heart rate by multiplying the HRmax by the desired exercise intensity. Holly aims for 70 percent intensity, so:
Target Heart Rate = HRmax × Intensity
Target Heart Rate = 190 bpm × 0.7 = 133 bpm.
However, this calculation is a general estimation. For a more accurate result, adjust the formula by considering resting heart rate (RHR). Subtract RHR from HRmax before multiplying by the exercise intensity:
Target Heart Rate = [(HRmax - RHR) × Intensity] + RHR
Given that Holly's RHR is not provided, let's assume an average RHR of 70 bpm.
Adjusted Target Heart Rate = [(190 - 70) × 0.7] + 70
Adjusted Target Heart Rate = (120 × 0.7) + 70
Adjusted Target Heart Rate = 84 + 70 = 154 bpm.
Thus, Holly's target heart rate at 70 percent intensity, considering an assumed RHR of 70 bpm, would be 154 bpm. This closely aligns with the calculated value from the Karvonen formula.
Therefore, the most accurate answer from the provided options is 154 bpm, which corresponds to option B.