Question 4 2 pts The half-life of a certain radioactive isotope is 580 years. Find the radioactive decay rate for this isotope, and use it to find how long it takes for a 100 gram sample of this substance to decay to exactly 75 grams. r Enter as a decimal and round to three decimal places) t yrs. (Enter as a decimal and round to three decimal places) Question 5 2 pts A small lake is stocked with a certain species of fish. The fish population is modeled by the function: P 10 1 + 4e 0.8t where P is the number of fish (in thousands) and t is measured in years since the lake was stocked. After how many years will the fish population reach 5000 (P - 5) fish? years (Enter a decimal rounded to two decimal places)