Heart beats about ________ times in one's life.

Explanation

A typical estimate is about 70 beats/minute x 60 minutes/hour x 24 hours/day x 365 days/year x 70 years = 2,574,720,000 beats, or about 2.6 billion beats. Since estimates vary with heart rate and lifespan, 2.8 billion is the closest listed value; students may choose 3.7 billion by using an unnecessarily high lifetime estimate.