Sue's grade in her math class is related to the number of hours she studies. The rate of change of her grade. GU}. is proportional to {100 - G}. where t is measured in hours and G(t} is her grade after t hours of study. The highest grade is a 100. 6(0) = 80. meaning she could get a 60 without any studying. After 10 hours Sue's grade would be en 60. How many hours would Sue need to study to get an A, which is a 90 or better? Round your answer up to the nearest hour, 012 020 025 030 If a population of endangered salmon. 5m, starts out with 80 fish and decreases at a rate proportional to 0.02 times the number of sh present each year, what is the particular solution to the differential equation which describes the number of sh overtime? Let t be measured in years. 0 S\") = sod0'02\" O S(t) = 303mm: 0 S(t.) = meet"3\" 0 S(t} = 10040-02\" A rate of change of H is given by % = k(15 + H). When t = O. H = 20. When t = 2. H = 50. Solve for k where H h -15. O 0.31 O 1.208 O 2.282 O 3.282 The rate of change of R is inversely proportional to R(x) where R > 0. If R(0) = 25, and R(2) = 10, find x, such that R(x) = 16. O -3 O -2.893 1.406 0 4