Question:
Solution
Notice that the graph is a line, and the equation for a line can be written as:
or
where m is the slope of the line, and b is the y-coordinate of the y-intercept of this line (where x = 0). In this case, notice that when x = 0 then y = 0, so b = 0. Then, we only need to find the slope of the line. By definition, the slope of a line is given by the following equation:
where (X1,Y1) and (X2,Y2) are any two points on the line. Take for example the points:
(X1,Y1) = (1,9)
(X2,Y2) = (2,18)
then, the slope of the given line would be:
thus, the equation for the given line (the relationship between the number of pounds and price) is:
where x is the pounds and f(x) is the price for a given pound. Thus, the unit price of steak is:
then the correct answer is A: $9 / 1lb