Question

A milk container is made of metal sheet in the shape of frustum of a cone whose volume is $10459 \frac{3}{7}cm^3$. The radii of its lower and upper circular ends are 8 cm and 20 cm respectively. Find the cost of metal sheet used in making the container at the rate of Rs. 1.40 per square centimetre. Use $\pi = \frac{22}{7}$
Or
A toy is in the form of a hemisphere surmounted by a right circular cone of the same base radius as that of the hemisphere. If the radius of base of the cone is 21 cm and its volume is $\frac{2}{3}$ of the volume of the hemisphere, calculate the height of the cone and the surface area of the toy. Use $\pi = \frac{22}{7}$

Answer 1

Answer:

Step-by-step explanation:

Volume of a frustum cone=volume of milk container.

1/3πh(R²+r²+Rr)=10459.42857

1/3×22/7×h((20²)+8²+20×8)=10459.42857

1/3×22/7×h(400+64+160)=10459.42857

1/3×22/7×h×624=10459.42857

h=10459.42857×21/22×624=16cm

h=16cm

Slant height(l)=√h²(R-r)²

=√16²(20-8)²

√256+144

=√400

=20cm

Slant height(l)=20cm

Cost of a metal sheet used in a container @ 1.40 per cm²=3218.285714×1.40=Rs.4505.6