Histograms of gyro-age for the individual M48 stars, calculated using the B10 rotational model and assuming an initial period of 1.1 d. The gray histogram shows all 62 stars, while the black histogram is for a sample restricted to the 46 stars in the particularly well-measured 0.55 < (B − V)₀< 1.00 region. The larger sample gives a median age of 451 Myr (mean = 441 Myr, S.D. = 117 Myr = 26%), and the smaller one gives similar values, with a median age of 457 Myr (mean = 447 Myr, S.D. = 70 Myr = 16%.) This large age dispersion mostly arises from having to assume a single initial period, P₀ (=1.1 d) for all stars.