Heart Rates For a certain group of individuals, the average heart rate is 71 beats per minute. Assume the variable is normally distributed and the standard deviation is 2 beats per minute. If a subject is selected at random, find the probability that the person has the following heart rate. Use a graphing calculator. Round the answers to four decimal places. Part: 0/3 Part 1 of 3 Between 68 and 72 beats per minute. P(6870)= Part: 2/3 Part 3 of 3 Less than 75 beats per minute. P(X<75)= Let ' X ' represent the heart rate. It is normally distributed with the following parameters X∼N(μ=71,σ=2) z-score =σx−μ​=(x−71)/2 This way we 1 st covert all the raw scores to z− scores and find the probability using std normal distribution tables. z-score is the standardised score which tells the deviation from mean in terms of SD. The prob that rate is between 68 and 72 since normal distribution is symmetrical around the mean, the tables only give values for P(Z Z)=1−P(Z−Z)=P(Z