A sample of a radioactive isotope had an initial mass of 620 mg in the year 2003 and decays exponentially over time. A measurement in the year 2005 found that the sample's mass had decayed to 390 mg. What would be the expected mass of the sample in the year 2010, to the nearest whole number?

In a survey of 1015 adults, a polling agency asked, "when you retire, do you think you will have enough money to live comfortably or not. of the 1015 surveyed, 534 stated that they were worried about having enough money to live comfortably in retirement. construct a 90% confidence interval for the proportion of adults who are worried about having enough money to live comfortably in retirement.