Answer: 144.
Step-by-step explanation:
Given : While exercising Julie found that her. Heart was beating 12 times every 5 seconds .
Number of times heart beats in 1 second =\(\dfrac{12}{5}\)
Since, 1 minute = 60 seconds
Then, Number of times heart beats in 60 second =\(\dfrac{12}{5}\times60=144\)
Hence, the number of times heart beats in 1 minute = 144.