24.

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







c = d + 3

c = 3d

c = d + 3d

d = 3c

1 answer

To determine which equation models the data in the table, we can look at how the cost (c) changes with the number of days (d).

Here’s the given data:

  • For d = 2, c = 6
  • For d = 3, c = 9
  • For d = 5, c = 15
  • For d = 6, c = 18

Let's analyze the relationship:

  1. Calculate cost per day:
    • From d = 2 to c = 6: \( \frac{6}{2} = 3 \)
    • From d = 3 to c = 9: \( \frac{9}{3} = 3 \)
    • From d = 5 to c = 15: \( \frac{15}{5} = 3 \)
    • From d = 6 to c = 18: \( \frac{18}{6} = 3 \)

The cost increases by 3 for every day, suggesting a linear relationship where the cost is three times the number of days.

Therefore, the equation can be expressed as:

\[ c = 3d \]

Now let's verify with each point:

  • For d = 2: \( c = 3 \times 2 = 6 \) (correct)
  • For d = 3: \( c = 3 \times 3 = 9 \) (correct)
  • For d = 5: \( c = 3 \times 5 = 15 \) (correct)
  • For d = 6: \( c = 3 \times 6 = 18 \) (correct)

Thus, the equation that models the data in the table is:

\[ \boxed{c = 3d} \]