Question

Twelve books cost $59.88 and

21 books cost $104.79. Is there is a
constant of proportionality between
these purchases? Explain.

Answer 1

Yes there is, and it is 4.99.

Explanation:

The constant of proportionality (let's call it
`\alpha`) will relate the number of books bought
`N` and their cost
`C` in the following way:

`C={\alpha}N`

`\therefore \alpha =(C)/(N)`

For the 12 books:

`\alpha =(59.88)/(12) = 4.99.`

And for the 21 books:

`\alpha =(104.79)/(21) = 4.99.`

The
`\alpha` for the two purchases is the same, thus there is a constant of proportionality between the two purchases.

P.S:
`\alpha` is the price per book.