Answer: 0.87 times per second (Or 52.2 times per minute)
Step-by-step explanation:
You need to make the conversion from minutes to seconds.
Remember that 1 minute has 60 seconds. Then 20 minutes to seconds is:

Find the number of times the heart beats in 1 second when it is rowing:

Find the number of times the heart beats in 1 second when it is resting:

Then the difference is:

(Or 52.2 times per minute)
Answer:
V=75.4 m^3
Step-by-step explanation:
V=pi*r^2*h
V=pi*2^2*6
V=4*6*pi
V=24*pi
V=75.39 or 75.4 m^3
Answer:
60 degrees
Step-by-step explanation:
49+11=60