Question

The cost of internet access at a café is a function of time. The costs for 8, 25, and 40 minutes are shown. Write an equation in slope-intercept form that represents the function. Then find the cost of surfing the web at the café for one hour. Time (min) 8 25 40 Cost ($) 4.36 7.25 9.80

Answer 1

• 
  `y=0.17x+3`
• The cost of surfing the web at the café for one hour:
  `\$13.2`

Explanation:

The equation of the line in Slope-Intercept form is:

`y=mx+b`

Where "m" is the slope and "b" is the y-intercept.

Take two points and substitute them into the formula for calculate the slope (The formula is
`m=(y_2-y_1)/(x_2-x_1)`).

Having these points:

`(8,4.36)` and
`(40,9.80)`

You can identify that:

`y_2=4.36\\y_1=9.80\\\\x_2=40\\x_1=8`

Then, the slope is:

`m=(4.36-9.80)/(40-8)=0.17`

Substitute the slope and the coordinates of any point on the line into the equation
`y=mx+b` and then solve for "b":

`4.36=0.17(8)+b\\\\4.36-1.36=b\\\\b=3`

Therefore, equation in Slope-Intercept form that represents the function is:

`y=0.17x+3`

Since 1 hour hour has 60 minutes, you need to substitute
`x=60` into the equation and then evaluate, in order to find the cost of surfing the web at the café for one hour. Then:

`y=0.17(60)+3\\\\y=13.2`