.
m=220-a
The given equation models a person’s maximum heart rate m, in beats per minute,
based on the person’s age a, in years. The National Institutes of Health (NIH) recommends
that a person’s target heart rate while exercising be at least 50% but no more than 75%
of the person’s maximum heart rate. The NIH recommends that Luisa’s target heart rate while exercising,
in beats per minute, should be at least 98 but no more than 147.
Based on the given information, what is Luisa’s maximum heart rate?
A) 122
B) 147
C) 196
D) 220
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Notice that in this problem, there are two different conceptions :
- (a) " a person’s maximum heart rate m "
and
- (b) " Luisa’s maximum heart rate while exercising ".
Having it in mind, see the solution below.
Let x be the Luisa's maximum heart rate,
the quantity under the problem's question.
Then from the problem, we have this inequality for x
0.75*x <= 147
which implies
x <= = 196.
ANSWER. Luisa’s maximum heart rate is 196 (option C).