Respuesta :
A circular pool with a diameter of 18 ft will have a uniform 4 ft concrete walkway poured around it. If the concrete cost $4.25 a square foot, how much will it cost for the concrete?
This can be solve be solving the area of walkway
Area of walkway is equal to = (pi)( 9 ft +4) ^2– (pi)(9ft)^2
= 276.46 sq ft
Cost = 276.46 sq ft * ($4.25 a square foot) = $1174.70
Answer:
$1,174.70
Step-by-step explanation:
Given : A circular pool with a diameter of 18 ft will have a uniform 4 ft concrete walkway poured around it.
To Find: If the concrete cost $4.25 a square foot, how much will it cost for the concrete?
Solution:
A circular pool has diameter of 18 ft will have a uniform 4 ft concrete walkway around it.
So radius = diameter /2 =18/2 =9 feet
Thus Area of circular pool = [tex]\pi r^{2}[/tex] = [tex]\pi 9^{2}[/tex]
Use π =3.14
Thus Area of circular pool = [tex]3.14*9^{2}[/tex]
= [tex]3.14*81[/tex]
= 254 . 37 square feet
Since the Radius of the pool with concrete = 9 + 4= 13
So, Area of circular pool with concrete= [tex]3.14*13^{2}[/tex]
= [tex]3.14*169[/tex]
= 530.66 square feet
Now surface area of concrete = area of pool with concrete - area of pool
Surface area of concrete= 530.66 - 254.34 = 276.32 square feet
If the concrete cost $4.25 a square foot of surface area,
So the cost for the concrete of 276.32 square feet = 276.32 * 4.25 = $ 1174.36
The option close to our answer is $1,174.70
Thus Option D is correct
