Answer:
60 to 80%
Explanation:
For maximum benefit, the heart rates during exercise regimes should be between<u> 60 to 80% </u>of an individual's maximum heart rate.
<em>The maximum heart rate varies from individuals to individuals and largely depends on age. It is calculated by subtracting one's age from 220. For example, a person that is 40 years old would have a maximum heart rate of;</em>
<em> 220 - 40 = 180 beats per minute.</em>
Such a person's heart rates during exercises should be between 108 and 144 beats per minute for maximum benefits.
Answer:
Probably none of the above. it's says directly proportional so there would be a proportionality constant.
A) 
The energy stored in a capacitor is given by:

where
Q is the charge stored
C is the capacitance
The capacitance of a parallel-plate capacitor is

where
is the vacuum permittivity
is the area of each plate
is the distance between the plates
Substituting,

The charge stored on the capacitor is

So, the energy stored is

B) 
This time, the separation between the plates is
d = 1.7 mm = 0.0017 m
So, the new capacitance is

And so, the new energy stored is

C)
Energy must be conserved, so the difference between the initial energy of the capacitor and its final energy is just equal to the work done to increase the separation between the two plates from 1.5 mm to 1.7 mm (in fact, the two plates of the capacitor attract each other since they have opposite charge, so work must be done in order to increase their separation)