Question

1. Explain whether each following example is proportional or non-proportional.

(a)y=7x-3
(b)The graph is for b
(c) A gallon of milk costs $1.99. A half-gallon of milk costs $3.89.
(d)
x y
2 13
3 19.5
4 26
5 32.5

Answer 1

9514 1404 393

Answer:

(a), (b), (c) are non-proportional

(d) is proportional

Explanation:

An equation or graph with a non-zero y-intercept is non-proportional. That is true for (a), (b), (c).

The table of (d) is proportional, with a constant of proportionality of 6.5.

__

Comment on (c)

In a proportional relation, price would go up with quantity, not down. If the prices both end in 9, one cannot be double the other, as would be required for the price of a gallon to be proportional to the price of a half-gallon.