71. A bucket is in the form of a frustum of a cone and holds 28.490 li

1.	71. A bucket is in the form of a frustum of a cone and holds 28.490 litres of water. Theradii of the top and bottom are 28 cm and 21 cm respectively. Find the height of theNCERT EXEMPLAR]bucket
Answer» R = 28 cmr = 21 cmLet height of frustum be h cm ∴Volume held by bucket = 28.490 litres = 28490 cm³Also, Volume of frustum = π(R²+Rr+r²)h/3=> 28490 = 22(784+588+441)h/(37)=> 1813h =2849021/22=> h = 27195/1813 = 15cm

71. A bucket is in the form of a frustum of a cone and holds 28.490 litres of water. Theradii of the top and bottom are 28 cm and 21 cm respectively. Find the height of theNCERT EXEMPLAR]bucket

Answer»

R = 28 cmr = 21 cmLet height of frustum be h cm

∴Volume held by bucket = 28.490 litres = 28490 cm³Also,

Volume of frustum = π(R²+Rr+r²)h/3=> 28490 = 22*(784+588+441)*h/(3*7)=> 1813h =28490*21/22=> h = 27195/1813 = 15cm