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. What is the approximate standard score for Scooter's heart rate?
A) -0.6
B) 0.6
C) 7
D) 11
E) 18

Question

Quizplus · Accepted Answer

The formula for finding standard score is:
z = (x - μ) / σ
where
x = Scooter's heart rate (126 beats per minute)
μ = the mean of the population (115 beats per minute)
σ = the standard deviation of the population (18 beats per minute)

Plugging in the values:
z = (126 - 115) / 18
z ≈ 0.611

Rounding to the nearest hundredth, the approximate standard score for Scooter's heart rate is 0.61, which means Scooter's heart rate is 0.61 standard deviations above the mean. Since the standard deviation is positive, the standard score is positive, and the best choice is B) 0.6.

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