A cylindrical bucket without cover is made of plastic plate. The diameter of the bottom of the bucket is 60cm and the height is 80cm. How many square meters of plastic plate is needed to make such a bucket?

A cylindrical bucket without cover is made of plastic plate. The diameter of the bottom of the bucket is 60cm and the height is 80cm. How many square meters of plastic plate is needed to make such a bucket?

First of all, the bucket ring area is 60 * 3.14 * 80 = 15072 square centimeters,
The square of base area (60 divided by 2) multiplied by 3.14 = 2826 square centimeters,
Add it up to 17898 square centimetres and turn it into 1.7898 square meters,
【60×3.14×80+（60÷2）²×3.14】÷10000=1.7898㎡

The ball falls into a cylindrical bucket of water. Four fifths of the ball's volume is immersed in water. The diameter of the bottom of the bucket is 60cm. When the ball is taken out of the water, the water level in the bucket drops by 2cm

Radius of cylinder bottom = 60 / 2 = 30
The volume of the ball immersed in water is:
3.14X30X30X2=5652
Sphere volume
5652 divided by 4 / 5 gives 7065 cubic centimeters

The diameter of the ball is 15 cm, and the diameter of the bottom of the bucket is 60 cm. The ball has a volume of 45 and is immersed in water. How many cm has the water surface in the bucket increased after the ball fell into the water? (Note: the volume of a sphere with radius R is 43 π R3)

15 △ 2 = 152 (CM); v = 43 π R3, 43 × 3.14 × (152) 3, = 43 × 3.14 × 33758, = 43 × 33758 × 3.14, = 562.5 × 3.14, = 1766.25 (CC); 1766.25 × 45 = 1413 (CC); 60 △ 2 = 30 (cm); 3.14 × 302, = 3.14 × 900, = 2826 (cm2); 1413 △ 2826 = 0.5 (CM); a: the water level in the bucket has risen by 0.5 cm