questions 77 & 81 please!

77. Depreciation The depreciation rate of a Mercury Sable is about 30% per year. If the Sable was purchased at $18,000, make a table of its value over the first 5 years after purchase. Find a function which gives its value t years after purchase, and sketch the graph of the function. (Source: Kelley Blue Book) 78. Depreciation The depreciation rate of a Toyota Camry is about 8% per year. If the Camry was purchased at $25,000, make a table of its value over the first 4 years after purchase. Find a function which gives its value t years after purchase, and sketch the graph of the function. (Source: Kelley Blue Book) 79. Savings Bonds U.S. Savings Bonds, Series I, pay interest at a rate of 3% compounded quarterly. How much would a bond purchased for $1000 be worth in 10 years? These bonds stop paying interest after 30 years. Why do you think this is so? (Hint: Think about how much this bond would be worth in 80 years.) 80. Salary The average hourly wage for construction workers was $18.22 in 2016 and has risen at a rate of 2.6% annually. (Source: Bureau of Labor Statistics) a. Express the hourly wage as a function of time t. Measure t in years since 2016 . b. Using your answer to part (a), make a table of predicted values of the hourly wage for the years 20162022. 81. Pharmacology When a drug is administered orally, the amount of the drug present in the bloodstream of the patient can be modeled by a function of the form C(t)=atebt where C(t) is the concentration of the drug (in milligrams per liter), t is the number of hours since the drug was administered, and a and b are positive constants. For a 300mg dose of the asthma drug aminophylline, this function is C(t)=4.5te0.275t (Source: Merck Manual of Diagnosis and Therapy) a. How much of this drug is present in the bloodstream at t=0 ? b. How much of this drug is present in the bloodstream after 1 hour? c. Sketch the graph of this function, either by hand or with a graphing utility, with t ranging from 0 to 30 . d. What happens to the value of the function as t ? Does this make sense in the context of this problem? Why? e. Use a graphing utility to find the time at which the concentration of this drug reaches its maximum. f. Use a graphing utility to determine when the concentration of this drug reaches 3mg/L for the second time. (This will occur after the concentration peaks.)