Question

What equation models the data in the table if d = number of days and c = cost? Days Cost 2 6 3 9 5 15 6 18

Answer 1

Answer: The equation models the data is given by

$c=3d$

Step-by-step explanation:

Since we have given that

Days  Cost

2          6

3          9

5         15

6         18

Let the number of days be 'd'.

Let the cost be 'c'.

So, we can see that there is direct variation between d and c :

$\dfrac{d}{c}=\dfrac{2}{6}\\\\\dfrac{d}{c}=\dfrac{1}{3}\\\\c=3d$

Hence, the equation models the data is given by

$c=3d$

Answer 2

Easier to do this problem if you'd share the data in columns, as shown:

Days Cost 2 6 3 9 5 15 6 18
    2      5
    6     15
    3       6
    9      18

Please, verify whether this assumption of mine matches the actual original problem.

Note that 2(3) = 6, and that 2(9) = 18, which match the 3rd and 4th rows, but do not match the first and second rows.  Were there a match for all four rows, the function would be y = 2x.

Please, verify whether this assumption of mine matches the actual original problem.