3. Radium-225 is a metal with a half-life of 1600 years. Suppose a researcher has 30 kilograms ofradium-225. How much will remain after 200 years? Round your answer to one decimal place. (3points)4. A rural community begins with a population of approximately 10,000 but declines at 6% per year.After how much time will the population reach half its size? (4 points)a) Use a formula that gives you the approximate half-life.bi Use the formula that gives the exact half-life, Round your answer to two decimal places