Rhythm InterpretationQuestion 3 of 100
Using the 300 method on a regular rhythm, a technician counts four large boxes between two consecutive R waves. What is the heart rate?
a.60 beats per minute
b.75 beats per minute
c.100 beats per minute
d.150 beats per minute
Explanation
The 300 method divides 300 by the number of large boxes between R waves, so 300 divided by 4 equals 75 beats per minute. Sixty would require five large boxes, 100 would require three, and 150 would require two. The method only works when the rhythm is regular, because it assumes every R-R interval is the same.
Practice all 100 questions free — no signup required.
Related questions on this topic
- A technician measures the distance from the beginning of the P wave to the beginning of the QRS complex on a strip and counts four small boxes. What is the PR interval, and is it normal?
- What is the normal duration of the QRS complex in an adult?
- A patient has an irregular rhythm. The technician counts 11 QRS complexes in a six-second strip. What is the approximate heart rate?
- What electrical event does the P wave represent on an EKG tracing?
- A technician is explaining a tracing to a student and points to the rounded wave that follows each QRS complex. What does this wave represent?
- Using the 1500 method, a technician counts 20 small boxes between two consecutive R waves on a regular strip. What is the heart rate?
Last reviewed: · editorial process
PrepPass Editorial Team · Verified against NHA Certified EKG Technician (CET) Exam · How we review