20, 21, 22 pls pls help

C webassign.net/web/Student/Assignment-Responses/submit?dep=27672353&tags=autosave#question3398908_18 20. [-/2 Points] DETAILS TANAPMATH7 3.R.038. MY NOTES ASK YOUR Growth of Bacteria A culture of bacteria that initially contained 9,000 bacteria has a count of 27,000 bacteria after 4 hr. (a) Determine the function Q(t) that expresses the exponential growth of the number of cells of this bacterium as a function of time t (In minutes). Q (t) - (b) Find the number of bacteria present after 8 hr. (Round your answer to the nearest thousand.) 21. [-/1 Points] DETAILS TANAPMATH7 3.R.039. MY NOTES ASK YOU Radioactive Decay The radioactive isotope carbon-14 has a half-life of 5,730 years. What is its decay constant? (Round your answer to seven decimal places.) k = 22. [-/3 Points] DETAILS TANAPMATH7 3.R.042. MY NOTES ASK YOU The U.S. infant mortality rate (per 1000 live births) is approximated by the function N(t) = 12.5e-0.0294t (0 s t = 21) where t is measured in years, with t = 0 corresponding to 1980. + What was the mortality rate in 1980? (Round your answer to one decimal place.) per 1000 live births What was the mortality rate in 1989? (Round your answer to one decimal place. ) per 1000 live births What was the mortality rate in 2000? (Round your answer to one decimal place.) per 1000 live births MacBook Air