Answer: a. 120 bpm
Explanation:
John's heart rate is 120 bpm and the right option is A. 120 bpm.
What is heart rate?Heart rate is the rate at which the heartbeat per minute.
To calculate the heart rate, we use the formula below.
Formula:
H' = Hb/t........... Equation 1Where:
Hb= HeartbeatsH' = Heart ratet = TimeFrom the question,
Given:
H' = 20 heartbeatst = 10 seconds = 10/60 = 1/6 miniutesSubstitute these values into equation 1
Hb = 20/(1/6)Hb = (20×6)Hb = 120 bpmHence, John's heart rate is 120 bpm and the right option is A. 120 bpm.
Learn more about heart rate here: https://brainly.com/question/723406
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