21. Solve the differential equation D = -y - B a. y = Ce * + 8 b. y = Ce" - 8 C. y = Co' + 8 d. y = Co" - B 22. The isotope "* C has a half-life of 5.715 years. Given an initial amount of 11 grams of the isotope, how many grams will remain after 500 years? After 5.000 years? Round to four decimal places. a. 7.2469 gm. 4.1988 gm b. 6.2117 gm. 3.5989 gm c. 10.3528 gm. 5.9982 grn d. 4.1411 gm. 2.3893 gm 23. The initial investment in a savings account in which interest is compounded continuously is $813. If the time required to double the amount is 9.25 years, what is the annual rate rounded to two decimal places? a. 7.49% b. 7.70% C. 13.34% d. 6.29% 24. A small pond can support a limited number of fish, If there are 200 fish in the pond to start and the differential equation describing the growth rate of the fish in the pond is dP(t) = 0.5(500 - P(!)), where P(() is the population and f is the time in years, to the nearest ten fish, how many fish will be in the pond at the end of one year? Round to the nearest integer. 255 345 325