Recommended heart rates during exercise very with age and physical condition for healthy person doing moderate to intense exercise Such as hiking the inequality is 0.5(220 minus a)is less than or equal to R is less than or equal to 0.9(220 minus a) gives a target range for the heart rate R (in beats per minuet)based on age (in years) what is the target range for beats for a person 15 years old? how old is a person whose turn it ranges between 99 and 178.2 beats