Hello. The question states that We have a globular cluster with total mass 10^6 times sun's mass. Assume that the main sequence lifetime of a solar mass star is 10 gigayear, and a main sequence lifetime scales with mass as M^-2. What is the mass of the most massive main sequence stars in the cluster after 1 gigayear? (answer - 3.2 times sun's mass) we have t ~ M^-2 Does this require me to do a differential and find out the maxima (of the mass) by putting it to zero? or by cutting of the massive stars which would die out within the 1 gigayear and somehow see the masses left.