What percent increased?

Question

The resting heart rate was 12 beats in 10 seconds. After drinking a Dr. Pepper my heart rate increased to 16 beats in 10 seconds. What percent did my heart rate increase?

Answer 1

12 to 16

16-12=4                                             _

4/12=1/3=0.333...=33 1/3% or 33.3%