The surface area of a 50cm long cylinder is increased by 40cm after it is sawed into two identical small cylinders

The surface area of a 50cm long cylinder is increased by 40cm after it is sawed into two identical small cylinders

From the meaning of the title:
The increased surface area is the size of two bottom areas;
So:
Bottom area = 40 △ 2 = 20 square centimeter
Cylinder volume
=Bottom area × length
=20×50
=1000 CC

After cutting a 5cm high small cylinder from a cylinder, the surface area is 188.4 square centimeters less than the original. What is the volume of the cut cylinder

The circumference of the bottom surface of the cylinder is 188.4 △ 5 = 37.68 cm
The bottom radius is: 37.68 △ 3.14 △ 2 = 6cm
The volume of the cut cylinder is 3.14 × 6 × 6 × 5 = 565.2 cubic centimeter

The height of a cylinder is 15cm. If the height is reduced by 5cm and the surface area is reduced by 785cm, the volume and surface area of the cylinder can be calculated
2. A cuboid pool, 15cm long, 8cm wide, 5cm high on the water surface. A cylindrical iron bar, 3cm in the bottom radius, 8cm high, put the iron bar into the cuboid pool, how many cm does the water surface rise
3. The garment factory produces a batch of garments. The original plan is to use 0.8m cloth for each set. After improving the cutting method, 0.2m cloth can be saved for each set, and now
How many sets can be made in China
4. One job, 3 / 5 in 1 / 3 hour, how many hours to finish the rest? (three ways: proportion, score, number of shares, these three I guess, the first and the second I'm sure)
Come on, before 8:30,

1. 785/3.14/5=50 50*50*3.14*15=117750 50*50*3.14*2+3.14*100*15=20410
2. 3*3*3.14*8/（15*8）=1.884
3. The title is not detailed=
4. （3/5）/（1/3）-1/3=22/15