Suppose a baseball is thrown at 89 miles per hour. The ball will travel 324 feet when hit by a bat swung at 51 miles per hour and will travel 444 feet when hit by a boat swung at 81 miles per hour. Let y be the number of feet traveled by the ball when hit by a bat swung at x miles per hour. How much farther will a ball travel for each mile-per-hour increase in the speed of the bat?

Respuesta :

Given:

Baseball is thrown at 89 miles per hour.

The ball will travel 324 feet when hit by a bat swung at 51 miles per hour.

It will travel 444 feet when hit by a boat swung at 81 miles per hour.

To find:

The addition distance travelled by the ball if the speed of bat increased by 1 unit.

Step-by-step explanation:

Let y be the number of feet traveled by the ball when hit by a bat swung at x miles per hour.  

The ball will travel 324 feet when hit by a bat swung at 51 miles per hour. So, the point is (51,324).

It will travel 444 feet when hit by a boat swung at 81 miles per hour. So, the point is (81, 444).

Equation of line passes through two points is

[tex]y-y_1=\dfrac{y_2-y_1}{x_2-x_1}(x-x_1)[/tex]

[tex]y-324=\dfrac{444-324}{81-51}(x-51)[/tex]

[tex]y-324=\dfrac{120}{30}(x-51)[/tex]

[tex]y-324=4(x-51)[/tex]

[tex]y-324=4x-204[/tex]

Add 324 on both sides.

[tex]y=4x-204+324[/tex]

[tex]y=4x+120[/tex]

Using the slope intercept form,  

[tex]y=mx+b[/tex]

where, m is slope.

The slope of equation [tex]y=4x+120[/tex] is 4. It means, the ball will travel 4 feet farther for each mile-per-hour increase in the speed of the bat.