Medical researchers have determined that for exercise to be beneficial, a person's desirable heart rate, R, in beats per minute, can be approximated by the formulas

R=143-0.65a for women

R=165-0.75a for men,

where a represents the person's age. If the desirable heart rate for a man is 135 beats per minute, how old is he?

a. 22.5 years old

b. 40 years old

c. 45 years old

d. 42.5 years old

Evaluate the function

f (x) = 1/2x+3

for f (4).

a. 5

b. 9

c. 11

d. 14

Question

Mathematics

Margaret Lowe

21 September, 21:27

Medical researchers have determined that for exercise to be beneficial, a person's desirable heart rate, R, in beats per minute, can be approximated by the formulas

R=143-0.65a for women

R=165-0.75a for men,

where a represents the person's age. If the desirable heart rate for a man is 135 beats per minute, how old is he?

a. 22.5 years old

b. 40 years old

c. 45 years old

d. 42.5 years old

Evaluate the function

f (x) = 1/2x+3

for f (4).

a. 5

b. 9

c. 11

d. 14

+1

Answers (1)

Know the Answer?

Tanya · Answer 1

we are given with two equations: R=143-0.65a for women and R = 165-0.75a for men. In this prblem we are asked the age of a man when R is equal to 135. In this case, we use the second equation and substitute R with 135. In this case, 135 = 165 - 0.75 a; a is equal then to 40 yrs old. In 2, when x is equal to 4, then 0.5*4 + 3 is equal to 5.