Statistics
posted by Kwame .
In 1972, there were 3.4 trillion cigarettes purchased worldwide, and in 1984, there were 4.3 trillion cigarettes purchased worldwide(in trillions) in the year x, where x=0 represents the year 1972.
(a) Which of the following linear equations could be used to predict the number of trillions of cigarettes y purchased worldwide in a given year x, where x=0 represents the year 1972?
A. y=3.4x+4.3
B. y=0.9x6.5
C. y=0.9x+3.4
D. y=0.075x+3.4
(b) Use the equation form part (a) to estimate the number of cigarettes purchased worldwide in the year 2008.
(c) Fill in the blanks to interpret the slop of the equation: The rate of change of cigarettes purchased worldwide with respect to time is _______ per_____. (include units of measurement.)

a) If x = 0 represents the year 1972, then x = 12 represents 1984.
If x = 0 or x = 12, the equation that fits would be D (substituting those two values for x and solving for y).
b) If x = 0 represents the year 1972, then x = 36 represents the year 2008. Substitute 36 for x in the equation and solve for y.
c) I'll let you figure out this one.