Final answer:
A 25 M☉ main-sequence star will lose 3 x 10^-6 M☉ of mass in its 3-million-year lifetime.
Step-by-step explanation:
The main-sequence lifetime of a 25 M☉ star is a few million years, according to Table 22.1. If this star is losing mass at a rate of 10^-6 M☉/yr, we can calculate the mass it will lose in its 3-million-year lifetime.
To find the mass lost, we can multiply the mass-loss rate by the star's lifetime. The mass lost is equal to (10^-6 M☉/yr) * (3 x 10^6 yr) = 3 x 10^-6 M☉.