The slant height of a cone is 5cm and the radius of its base is 3cm. Find, correct to the nearest whole number, the volume of the cone. ( Take (pi = frac{22}{7}))
-
A.
48cm3 -
B.
47cm3 -
C.
38cm3 -
D.
12cm3
Correct Answer: Option C
Explanation
Volume of a cone = (frac{1}{3} pi r^2h)
h2 = 52 = 32
= 25 – 9 = 16
h = (sqrt{16})
h = 4cm
v = (frac{1}{3} times frac{22}{7} times 3^2 times 4)
(frac{1}{3} times frac{22}{7} times 9 times 4)
= (frac{22 times 3 times 4}{7})
= 37.7cm3
= 38cm3