Suppose that the distribution of heart rates for medium-sized dogs is Normally distributed with mean 115 beats per minute and standard deviation 18 beats per minute.
Stacy takes her medium-sized dog, Scooter, to the veterinarian for a wellness check and learns that Scooter's heart rate is 126 beats per minute. Approximately what percentage of medium-sized dogs have a heart rate that is lower than Scooter's?
A) -60%.
B) 27.42%.
C) 60%.
D) 72.58%.
E) 99.4%.

Question

Quizplus · Accepted Answer

We need to calculate the z-score of Scooter's heart rate and then find the area under the normal curve to the left of this z-score.

z = (126 - 115)/18 = 0.61

Using a standard normal table or calculator, we can find that the area to the left of z = 0.61 is 0.7257, or approximately 72.58%.

Therefore, approximately 72.58% of medium-sized dogs have a heart rate that is lower than Scooter's.

Suppose That the Distribution of Heart Rates for Medium-Sized Dogs