The heart rate of a person can be modeled by the function r(a)=211−0.64a

Question

where a
is the person's age in years and r(a)
is heartbeats per minute. The life span in minutes of a person is modeled by the function s(a)=525,600a
.

Explain what (r⋅s)(a)
represents.



(1 point)
Responses

the total number of heartbeats in a lifetime of a person who is a
years old
the total number of heartbeats in a lifetime of a person who is A years old

the heart rate of a person who is a
minutes old
the heart rate of a person who is A minutes old

the heart rate of a person who is a
years old
the heart rate of a person who is A years old

the total number of heartbeats in a lifetime of a person who is a
minutes old

Answer 1

The expression \((r \cdot s)(a)\) represents the product of the heart rate function \(r(a)\) and the lifespan function \(s(a)\).

• \(r(a) = 211 - 0.64a\) represents the heart rate in beats per minute for a person who is \(a\) years old.
• \(s(a) = 525,600a\) represents the lifespan in minutes of a person who is \(a\) years old.

Therefore, the product \((r \cdot s)(a)\) can be interpreted as the total number of heartbeats in a lifetime of a person who is \(a\) years old. To find the total number of heartbeats, you would multiply the heart rate (in beats per minute) by the total minutes in their lifespan.

Thus, the correct response is: the total number of heartbeats in a lifetime of a person who is a years old.