Question

Mayank a student of class 7th loves watching and playing with birds of different kinds.
One day he had an idea in his mind to make a bird-bath on his garden. His brother who is
studying in class 10th helped him to choose the material and shape of the birdbath. They
made it in the shape of a cylinder with a hemispherical depression at one end as shown
in the Figure below. They opted for the height of the hollow cylinder as 1.15 m and its
radius is 30 cm.
30 cm
1.45 m
By using the above-given information, find the following:
i The curved surface area of the hemisphere is:
0.36 m2
b. 0.46 m2
0.26 m2
0.56 m2
The curved surface area of the cylinder is:
a 0.787 m2
0.87
2
T m2
c. 0.8772 m2
0.877 m2
The total surface area of the bud-bath is: (Take a =
bha
2.3 m2
b. 3.3 m2
3.5 In2
d. 5.3 m2​

Answer 1

Height, h = 1.45 m Radius , r = 30 cm = = 0.3 m

Total Surface area of the bird bath = T.S.A = of Cylinder

T.S.A of Cylinder = 2nr(r+h)

= 2 x 22 /7x 0.3 (0.3+1.45)

= 3.3 m2

As the cylinder is attached to a hemispherical depression , its area is not added.If the cylinder was attached to a base , it would have been calculated...