If the second R wave lands on mark 75 after the first R wave, what is the heart rate?

• A. 60 bpm
• B. 75 bpm
• C. 90 bpm
• D. 100 bpm

Answer: (B)

To determine the heart rate from the given information, you need to analyze the timing between the R waves in the EKG tracing. The R wave marks the peak of the QRS complex, and the interval between R waves is crucial for calculating heart rate.

If the second R wave occurs 75 marks after the first R wave, this indicates that there is a specific time interval between the two heartbeats. In EKG interpretation, each small mark often corresponds to 0.04 seconds, and there are 5 small marks in one large square on the EKG grid, representing 0.20 seconds.

When the second R wave lands 75 marks later, it signifies that the time between the two R waves is 75 x 0.04 seconds, which equals 3 seconds. To find the heart rate, you can use the formula:

Heart Rate (bpm) = 60 seconds / R-R interval (seconds).

In this case, the R-R interval is 3 seconds, so you calculate:

Heart Rate = 60 / 3 = 20 beats per minute.

However, we need to clarify that the marks referred to in the question might suggest a different understanding or a misunderstanding in the intervals. When analyzing