Question

The stopping distance on wet pavement at 20mph is about 60feet. The stopping distance at 30mph is 120feet. What would you estimate the stopping distance is at 40mph? Construct a formula

Answer 1

Answer:

$y = 6x - 60$ --- formula

The stopping distance at 40mph is 180ft

Step-by-step explanation:

Given

$(x,y) = (20,60)$

$(x,y) = (30,120)$

Solving (a): Construct a formula

Calculate the slope (m)

$m = \frac{y_2 - y_1}{x_2 - x_1}$

$m = \frac{120 - 60}{30-20}$

$m = \frac{60}{10}$

$m=6$

So, the equation is:

$y = m(x - x_1) + y_1$

$y = 6(x - 20) + 60$

Open bracket

$y = 6x - 120 + 60$

$y = 6x - 60$

Hence, the formula to use is: $y = 6x - 60$

Solving (b): y, when x = 40

$y = 6x - 60$

$y = 6 * 40 - 60$

$y = 180$