U.S. health-care expenditures for 1970-2008 (reported by the Centers for Medicare and Medicaid Services) are given in the table below. Health-care Health-care expenditures expenditures Year X billions of $) Year X (billions of $) 1970 75 1996 26 1069 1975 133 1998 78 1190 1980 10 253 2000 30 1353 1985 15 439 2002 32 1602 1990 20 714 2004 34 1855 1992 22 849 2006 36 2113 1994 24 962 2008 38 2400 (a) Make a scatter plot of the data. f(X 2500. 2000 2000 1500 1500 1000 1000 500 500 L X 5 10 15 25 30 35 O 10 20 30 10 O f(X f(x 2500 2500 2000 2000 1500 1500 1000 1000 500 500 X X O 10 20 30 40 O 10 20 30 40Is a linear model appropriate? Yes 0 No (b) Use a calculator to nd an exponential curve x) = b - a\" that models U.S. healthcare expenditures x years since 1970. (Round your terms to three decimal places.) x} = billion dollars (c) Use your model to estimate U.S. healthcare expenditures in 2001. (Round your answer to three decimal places.) |:| trillion dollars (d) Use your model to predict U.S. health-care expenditures in 2009. {Round your answer to three decimal places.) |:| trillion dollars Fill in the table by finding the appropriate logarithmic or exponential form of the equation, as in Example 4. Logarithmic Exponential form form log, 9 = 1 log, 729 = 3 91/2 = 3 9- = 81 1099 = -1 1 81The pH reading of a sample of each substance is given. Calculate the hydrogen ion concentration of the substance. (Give your answers in scientific notation, correct to one decimal place.) (a) Soda: PH = 2.4 [H+] = x 10 M (b) Milk: PH = 6.6 [H*] = x 10 M