Answer:
A
Step-by-step explanation:
Volume of cylinder= πr²h, where r is the radius
Volume of concrete
= volume of large cylinder -volume of smaller hollow cylinder
Large cylinder:
Diameter= 7m
Since radius= ½(diameter),
Radius= 7 ÷2= 3.5m
Height= 3m
Volume of large cylinder
= π(3.5)²(3)
= 36.75π m³
Small hollow cylinder:
Diameter= 4m
Radius= 4 ÷2= 2m
Height= 3m
Volume of small hollow cylinder
= π(2)²(3)
= 12π m³
Substitute vol. of large and small hollow cylinder with 36.75π and 12π respectively, then substitute 22/7 for π:
Volume of concrete
= 36.75π -12π
= 24.75π
[tex] = 24.75( \frac{22}{7} ) \\ = 77.79 \: m^{3} [/tex]
( to 2 d.p.)
