The diameter of the lower and upper ends of a bucket in the form of a frustum of a cone are 10 cm and 30 cm respectively. If its height is 24 cm. find:

(i) The capacity of the bucket


(ii) The area of the metal sheet used to make the bucket. [Take π = 3.14.]

Given,


Radius of lower end, r2 = 10 cm


Radius of upper end, r1 = 30 cm


Height of bucket, h = 24 cm


(i) As we know


volume of frustum of a cone =


Where, h = height, r1 and r2 are radii of two ends (r1 > r2)


Capacity of bucket =


=3.14 × 8 × (100 + 900 + 300)


= 3.14 × 8 × 1300 = 32656 cm3


(ii) Area of metal used to make bucket = CSA of frustum + base area


We know that,


Curved surface area of frustum = πl(r1 + r2)


Where, r1 and r2 are the radii of two ends (r1 > r2)


And l = slant height and


l = √(h2+ (r1 – r2 )2)


So, we have


Slant height, l=√(242 + (30 – 10)2)


l =√(576 + 100)


l =√676


l =26 cm


And as the base has lower end,


Base area = πr22, where r2 is the radius of lower end


Therefore,


Area of metal sheet used = πl(r1 + r2) + πr22


= π(26)[10 + 30] + π(10)2


= 1040π + 100π = 1140π


= 1140(3.14) = 3579.6 cm2


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