Question

the graph represents a persons heart rate in beats per minute during 30 minutes of exercise. which statement best describes the relationship between heart rate and time during exercise? the heart rate increases for 6 minutes, remains constant for 19 minutes, and then gradually increases for 5 minutes. the heart rate decreases for 6 minutes, remains constant for 19 minutes, and then gradually increases for 5 minutes. the heart rate increases for 6 minutes, remains constant for 19 minutes, and then gradually decreases for 5 minutes. the heart rate remains constant for 6 minutes, increases for 19 minutes, and then gradually decreases for 5 minutes.

Explanation:

Step1: Analyze the graph

Observe the trend of the heart - rate over time.

• From \(t = 0\) to \(t=6\) (minutes), the heart - rate is increasing (the line has a positive slope).
• From \(t = 6\) to \(t=25\) (minutes), the heart - rate is constant (the line is horizontal).
• From \(t = 25\) to \(t=30\) (minutes), the heart - rate is decreasing (the line has a negative slope).

Step2: Check each option

• Option 1: "The heart rate increases for 6 minutes, becomes constant for 19 minutes, and then gradually increases for 5 minutes" is wrong because after the constant period, it decreases.
• Option 2: "The heart rate increases for 6 minutes, becomes constant for 19 minutes, and then gradually decreases for 5 minutes" is correct.
• Option 3: "The heart rate decreases for 6 minutes, remains constant for 19 minutes, and then gradually decreases for 5 minutes" is wrong because it starts with an increase.
• Option 4: "The heart rate remains constant for 6 minutes, increases for 19 minutes, and then gradually decreases for 5 minutes" is wrong because it starts with an increase.

Answer:

The heart rate increases for 6 minutes, becomes constant for 19 minutes, and then gradually decreases for 5 minutes.