Respuesta :
Answer:
Starting bpm = 91
Resting bpm = 72.8
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Explanation:
A 30% increase is represented by the multiplier 1.30 because
100% + 30% = 1.00 + 0.30 = 1.30
So Krystal's initial heart rate is 1.30*70 = 91 bpm.
If you wanted, you can think of it like this
30% of 70 = 0.30*70 = 21 is added onto the initial 70 bpm to get 70+21 = 91 bpm.
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To decrease by 20%, we use the multiplier 0.80 since
100% - 20% = 1.00 - 0.20 = 0.80
Losing 20% of something means we keep the remaining 80%
So,
80% of 91 = 0.80*91 = 72.8 bpm.
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Here's one way to find the final bpm in one single line
1.30*0.80*70 = 72.8
in which you could write it like this
(1 + 0.30)*(1 - 0.20)*(70) = 72.8
The second way may be a bit longer, but I find it's more descriptive to see where the percentage increases vs percentage decreases are.
