During the past 10 years, the amount of money, M (in billions of dollars), spent in North America by car dealerships advertising their product can be modeled by the equation M = 0.15e^0.3t + 0.78. In what year was about $3 billion (M = 3) spent by car dealerships in advertising?
A. t = 9
B. t = 10
C. t = 8
D. t = 3
Solve for t: 3 = 0.202479 t+0.78 3 = 0.202479 t+0.78 is equivalent to 0.202479 t+0.78 = 3: 0.202479 t+0.78 = 3 Subtract 0.78 from both sides: 0.202479 t+(0.78-0.78) = 3-0.78 0.78-0.78 = 0: 0.202479 t = 3-0.78 3-0.78 = 2.22: 0.202479 t = 2.22 Divide both sides of 0.202479 t = 2.22 by 0.202479: (0.202479 t)/0.202479 = 2.22/0.202479 0.202479/0.202479 = 1: t = 2.22/0.202479 2.22/0.202479 = 10.9641: Answer: | | t = 10.9641 Years
Even though the answer is closer to 11 years, it will do to say the answer is B as can be seen.
