Digital PSAT Math Practice Question 4: Answer and Explanation

Question: 4

A cardiologist uses the guidelines for maximum recommended heart rate (measured in beats per minute) shown in the table above, which vary based on a patient's age. One of the cardiologist's patients, age 55, wants to start an exercise program. The cardiologist recommends that the patient maintain a heart rate greater than 50% and less than 85% of the maximum recommended heart rate while exercising. Which of the following expressions gives the range in which the patient's heart rate, H, should be during exercise?

• A. 50 < H < 85
• B. 80 < H < 136
• C. 85 < H < 160
• D. 150 < H < 160

Correct Answer: B

Explanation:

(B) Use the table to find the maximum recommended heart rate for a 55-year-old person-160 beats per minute. Then take 50% and 85% of 160 to determine the lower and upper bounds of the recommended heart rate:

So the range is between 80 and 136 beats per minute, which is expressed as the inequality 80 < H < 136.