The Unruly Queens chess club is hosting a tournament, and each club member is bringing something to eat or drink. Kristen decides to bring oatmeal raisin cookies from her favorite bakery.

Question

There is a proportional relationship between the number of oatmeal raisin cookies Kristen buys, x, and their total cost (in dollars), y.
x (cookies) y (dollars)
10 $10
11 $11
17 $17
19 $19
What is the constant of proportionality? Write your answer as a whole number or decimal.
dollars per cookie

Answer 1

To find the constant of proportionality in this scenario, we look at the relationship between the number of cookies \( x \) and the total cost \( y \).

The constant of proportionality can be calculated by dividing the total cost \( y \) by the number of cookies \( x \).

From the provided data:

\[ \text{Constant of proportionality} = \frac{y}{x} \]

Calculating for the provided pairs:

1. For \( x = 10 \), \( y = 10 \): \[ \frac{10}{10} = 1 \]

2. For \( x = 11 \), \( y = 11 \): \[ \frac{11}{11} = 1 \]

3. For \( x = 17 \), \( y = 17 \): \[ \frac{17}{17} = 1 \]

4. For \( x = 19 \), \( y = 19 \): \[ \frac{19}{19} = 1 \]

In each case, we find that the constant of proportionality is \( 1 \) dollar per cookie.

Thus, the constant of proportionality is:

\[ \boxed{1} \]