Ask everyone a few 6th grade math questions, preferably with arithmetic methods! 20

1.An increase in height of 2cm increases the surface area, but in fact, the increase in the surface area is the increase in the side area, so dividing by 2 is the side length of the original side area. So it turns out that the side area of this cylinder is multiplied, and the final result is calculated by yourself!

2.The reduction in surface area is due to the fact that the rectangular sides of the two semi-cylinders are hidden, so the rectangular side area of the semi-cylinder is 1 square centimeter. The radius of the base surface of the cylinder is 3 cm, and the diameter is 6 cm, so the length of the other side of the rectangle = 1 square centimeter 6 cm = 1 6 cm, which is the height of the cylinder.

The circumference of the bottom surface of the cylinder = 2 r = 2 times 3, so the side area of the cylinder = 1 6 times 2 r

3.The radius of the base surface is 1 decimeter, and the area of a base surface = the square of r multiplied by . So the side area is the area of the two bottom surfaces. According to the radius, we can know the perimeter of the bottom surface, that is, the length of one side of the side, and divide the side area by the side length of this side to the height of the cylinder.

4.The height is reduced by 2cm, and the area reduced is the area of the side that is reduced, and the square centimeter is 2cm, which is the circumference of the bottom surface of the cylinder, which is centimeters. Multiply by 10 = square centimeters, which is the side area of the original cylinder.

Let's find the bottom area, the circumference of the bottom surface, so use the radius of the bottom surface, and know the bottom area of the radius. The area of the two bottom surfaces + side area is the area of the original cylinder.

1.(divide by 2).

2.The height of the cylinder is: 1 divided by (2 times 3), and this height is multiplied by the circumference of the circle: 2 times multiplied by 3

3.The height of the cylinder = (surface area - circle area multiplied by 2) divided by the base circumference.

Dizzy.. Study hard.,It's always good to read books by yourself.。。。

1;This is the circumference of the bottom surface of the cylinder, and it is also the length of the sides of the square" Note: * is multiplication.

It's better to do it yourself and don't let your head rust.

There are 25 students in the sixth grade who can play at least one type of chess.

There are 18-5=13 people who can only play chess.

There are 12-5=7 people who can only play Go.

There are 5 people under both classes.

In the sixth grade, there are 13 + 7 + 5 = 25 people who can play at least one type of chess, and four-fifths are 16% of 5 meters

1200 square decimeters = 12 square meters.

18+12-5=25 people.

Four-fifths is 5 meters of (16)% 1200 square decimeters = (12) square meters.

Speed Adoption Ahh

Don't take it indiscriminately.

Only me and the 3rd floor are correct, you don't believe it, ask the teacher tomorrow, you know.

18+12-5=25

80 12 I kind of forgot, I'm in my first year of junior high school.

1 5 18 25 - (minus) 5 24 5 62(60%+4 9 50%) 37 60-(minus)5 6(6 Qiaohui 10+4 9 1 2) 60 37-5 61 Xiaozhaoa2

3.(40%+1 3) 2 3 (1-(minus)75%)3 Guess Xiang 2

4.One number is 600, which is 20% more than the other. Find another number. (column equation) solution: Let another number be x.

x(1+20%)=600

x=600÷

x=500

If Team A completes the project in 12 days alone, Team A completes the project (ergonomics) 1 12 per dayArmor. After 5 days of cooperation between the two teams, the remaining project was completed by Team A, and it took 3 days, indicating that in the completion of this project, Team A did 5 3 8 (days) and Team B did 5 days.

Team A completed 1 12 8 2 3 of the works

Team B completed 1 2 3 1 3 of the works

Team B's (ergonomics) 1 3 5 1 15 The number of days required for Team B to complete the project alone is 1 1 15 15 (days) Comprehensive: 1 { 1 1 12 (5 3) 5}15 (days) Therefore, it takes 15 days for Team B to complete the project alone.