When interest is compounded continuously, the amount of money increases at a rate proportional to the amount Spresent at time t, that is, ds/dt-rs, wherer is the annual rate of interest. (a) Find the amount of money accrued at the end of 8 years when $3000 is deposited in a savings account drawing 5 % annual interest compounded continuously. (Round your answer to the nearest cent.) (b) In how many years will the initial sum deposited have doubled? (Round your answer to the nearest year.) years (c) Use a calculator to compare the amount obtained in part (a) with the amount S = 3000 3000(1+4210.0573) that is accrued when interest is compounded quarterly. (Round your answer to the nearest cent.) S=$ Loon The radioactive isotope of lead, Pb 209, decays at a rate proportional to the amount present at time and has a half life of 3.3 hours. If 1 gram of this isotope is present initially, how long will it take for 80% of the lead to decay? (Round your answer to two decimal places.) 8.50 Xhi