To earn a fitness reward, your average heart rate while walking must be between 80 and 89 beats per minute, inclusive. Suppose you recorded 85, 81, and 87 beats per minute on your first three recordings. What are the possible heart rates you can have on the fourth and final recording in order to earn a fitness reward?

Between 67 and 103 beats per minute

Step-by-step explanation:

The minimum would be 80. That means that the minimum sum would have to be 320 among the four numbers.

85+81+87=253

320-253=67 so 67 will be the minimum

now, we should see the maximum. It will be 89 so the sum of the four numbers cannot be anymore than 89*4 which is 356

So, 356-253=103