Normal: Mean=7.4058, SD=0.5305 Density 0.85 0.8 0.77 0.6 0.54 0.4 0.4 0.36 0.36 0.3 0.21 0.2 0.13 0:04 0.01 0.02 0.01 0.01 knee dia (in) The above continuous probability distribution of the diameter of a human knee (in inches) is based on measurements of 507 subjects As shown, a normal curve with a mean of about 7.4 and standard deviation of about 0.53 fits reasonably well atop the distribution. Use the Statcrunch normal probability calculator to find the probability that someone's knee is less than 7 inches in diameter. Or, alternatively, use any other means at your disposal to compute the normal probability. Probability values in the answers have been rounded. O .77 O .16 O .84 O .23