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 1
Where:
- Hb= Heartbeats
- H' = Heart rate
- t = Time
From the question,
Given:
- H' = 20 heartbeats
- t = 10 seconds = 10/60 = 1/6 miniutes
Substitute these values into equation 1
- Hb = 20/(1/6)
- Hb = (20×6)
- Hb = 120 bpm
Hence, 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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