1). The 1906 San Francisco earthquake had a magnitude of 8.3 on the Richter scale. At the same time in South America there was an eathquake with magnitude 6.5 that caused only minor damage. How many times more intense was the San Francisco earthquake than the South American one? Round the answer to the nearest hundredth.

2). The population of the world in 1987 was 5 billion and the relative growth rate was estimated at 2% per year. Assuming that the world population follows an exponential growth model, find the projected world population in 2007. Round your answer to 2 decimal places.
Your answer is billion people

3). A wooden artifact from an ancient tomb contains 35 percent of the carbon-14 that is present in living trees. How long ago, to the nearest year, was the artifact made? (The half-life of carbon-14 is 5730 years.)

4). The half-life of Radium-226 is 1590 years. If a sample contains 300 mg, how many mg will remain after 2000 years?