Proteins in the knee provide measures of lubrication and wear. In the article “Composition of Joint Fluid in Patients Undergoing Total Knee Replacement and Revision Arthroplasty” (Biomaterials, Vol. 25, No. 18, pp. 4433–4445), D. Mazzucco, et al. hypothesized that the protein make-up in the knee would change when patients undergo a total knee arthroplasty surgery. The mean concentration of hyaluronic acid in the knees of patients receiving total knee arthroplasty is 1.3 mg/mL; the standard deviation is 0.4 mg/mL. Assuming that hyaluronic acid concentration is normally distributed, find the percentage of patients receiving total knee arthroplasty who have a knee hyaluronic acid concentration
a. Below 1.4 mg/mL
b. Between 1 and 2 mg/mL
c. Above 2.1 mg/mL