A massive main-sequence star has a total estimated stable main-sequence lifetime of 24 million years24\text{ million years}24 million years, during which inward gravitational forces and outward radiation and thermal pressure forces remain balanced.
This star has currently been in this balanced state for 68%68\%68% of its total stable main-sequence lifetime.
Calculate for how many millions of years these forces have been balanced in this star.
42 exam-style questions on Edexcel GCSE Physics 7.3 Stars. Each one has a worked solution and a mark scheme showing where the marks go.