A rock sample has a half-life of 30 years, and it originally had 1,000g of radioactive material. After 90 years, how much of the original material is left?

Scientists who study the anatomy of the systems in the human body focus their studies on

Two people are negotiating to resolve a conflict. they both have their own ideas about what caused the conflict, but their ideas are very different. which they do to gain more insight into because of the conflict?

Which of these activities would better would maintain and improve muscle endurance