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

Multiple Choice

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%.