Answer:
80 rods of steel.
Explanation:
Here is the complete question
A company makes steel rods shaped like cylinders. Each rod has a radius of 3 centimeters and a height of 20 centimeters. If the company used 45,781.2 cm³ of steel, how many rods did it make?
Solution
Since the steel rod is a cylinder whose volume, V = πr²h where r = radius of cylinder = 3 cm and h = height of cylinder = 20 cm.
We substitute these into V to find the volume of one rod.
So, V = πr²h
= π(3 cm)² × 20 cm
= π × 9 cm² × 20 cm
= 180π cm³
= 565.49 cm³
Since 45,781.2 cm³ of steel was used, this total volume of steel, V' equals the number of rods, n times the volume of one rod, V.
So, V' = nV
Making n subject of the formula, we have
n = V'/V
Substituting V' and V into the equation, we have
n = 45,781.2 cm³/565.49 cm³
n = 80.96
We round n = 80.96 down to 80 since we cannot have a decimal number of rods.
So, n = 80 rods
So, the company made are 80 rods of steel.