Question

This table shows the relationship between the diameter of a tire and its cost a Kim’s discount hubcapsWhat is the best prediction of the cost of hubcap with a diameter of 20 inches

Answer 1

Concept:

We will have to get the formula connecting the diameter and the cost

Step 1:

We will bring put two coordinates below as

`\begin{gathered} (x_1,y_1)\Rightarrow(14,40) \\ (x_2,y_2)\Rightarrow(16,50) \end{gathered}`

To figure out the equation of the line, we will use the formula below

`(y_2-y_1)/(x_2-x_1)=(y-y_1)/(x-x_1)`

By substituting the values, we will have

`\begin{gathered} (y_(2)-y_(1))/(x_(2)-x_(1))=(y-y_(1))/(x-x_(1)) \\ (50-40)/(16-14)=(y-40)/(x-14) \\ (10)/(2)=(y-40)/(x-14) \\ y-40=5(x-14) \\ y-40=5x-70 \\ y=5x-70+40 \\ y=5x-30 \end{gathered}`

Step 2:

To get the cost of a hubcap with a diameter of 20 inches , we will substitute x=20 in the equation below

`\begin{gathered} y=5x-30 \\ y=5(20)-30 \\ y=100-30 \\ y=70 \end{gathered}`

Hence,

The final asnwer is

`\Rightarrow70`

The FIRST OPTION is the right answer