sample vs population covariance

CFA Vol 4- Reading 50- problem 1 calculating std deviation and covariance of 6 months of returns - The answer key treats it like a population variance/covariance and divides by n=6 for both calculations. In the text on p.234, it states treat like sample data and divide by n-1 (5 in this case). Anyone know if there is an explanation? or is the answer key wrong?

errata… Study Session 12, Reading 50: In the solutions on p. A-14, the calculations for standard deviation in 1B and covariance in 1C should use (n – 1) rather than n in the denominators. The standard deviation for Madison is thus √(0.0257/5) = 0.0715 and the standard deviation for GE (named “Sophie Electric” in the problem) is √(0.04120/5) = 0.0908. COVij = (1/5)(0.0222) = 0.0044.