Elementary School Math Problems! Urgent! Math problems for elementary school students, anxious and u

1.Fill a cylindrical cup with r of 10cm with water, put a conical plumb with a bottom r of 5cm in the water, when the plumb is taken out of the water, the water in the cup falls, what is the h of this plumb?

The volume of the plumb weight is.

10 10 cubic centimeters.

The bottom area of the plumb weight is:

5 5 square centimeters.

The height of the plumb is.

157 3 cm.

2.If 9 more boys participate, there will be 1 6 fewer boys than boys, how many girls will participate in the competition?

then the boy is 1 6 less than the boy" should be "then the girl is 1 6 less than the boy".

There is no change in the girls, and the girls are seen as unit 1

It turned out that the boys were girls.

Now boys are girls.

Girls have. 9 (6 5 10 9) people.

How is it not an integer???

There is an error in the question.

1. The volume formula of the cone is: v=1 3* *h*(r 2) to calculate the volume of the falling section v=

So 1 3* *h*(r 2) = 50

What does it mean to get h=2 and "1 6 less boys than boys"?

Cone = 10*10*

h cone = v s = v (r*r*

2.The title is incorrect"then boys are 1 6 less than boys"

Question 1. 6cm。

The volume of the plumb is equal to the volume of water falling.

Plumb weight: 1 3*s*h, s= r 2=25, water volume: sh, s= r 2=100. h=, with a volume of 50.

1/3*25π*h=50π

So, h=6

Question 2. You made a mistake.

Question 1: The volume of the plumb weight is the volume of water in a cylindrical cup with r of 10cm.

10 10 cubic centimeters.

The bottom area of the plumb weight is:

5 5 square centimeters.

The height of the plumb is.

157 3 cm.

Do it with "1 6 fewer girls than boys".

There is no change in the girls, and the girls are seen as unit 1

It turned out that the boys were girls.

After adding 9 boys, boys are girls.

There are 9 (6 5 10 9) girls.

Calculus, girls , boys.

Person. There are no mistakes purely in numbers.

Considering reality, people can't be decimals.

There is still a problem with the topic itself.

I don't know what grade you are, but this problem is calculated by the method of column equations, and if you don't understand, just take a look at what you will learn in junior high school.

Analysis: Judging from the title, I don't know if the white cloth, flower cloth, and sold out in a few days. But the title says that "in a few days, all the white cloth will be sold out, and there will be 120 meters of flower cloth left", so you can start in a few days.

Solution: Set x days of white cloth to be sold out, (then the total amount of white cloth is 30x meters, and the flower cloth (40x+120) meters).

According to the title, 40x+120=2*30x

The solution is x=6, so the stock flower cloth has: 40 * 6 + 120 = 360 (meters) Answer: The stock flower cloth has 360 meters.

120÷(30×2-40)

6 (days) 360 (meters).

A: There are 360 meters of stock flower cloth.

If you sell 30 meters of white cloth and 40 meters of flower cloth every day, the flower cloth sold every day is 40 30 = 4 3 of the white cloth, so the remaining flower cloth is 2-4 3 = 2 3 of the white cloth, so the original white cloth 120 2 3 = 180 meters, the original flower cloth 180 * 2 = 360 meters.

If you sell these two kinds of cloth according to the relationship of 2 times, the last two kinds of cloth will be sold out at the same time 30 2 = 60 meters ......If the white cloth is sold for 30 meters, the flowers will be sold for 60 meters.

60-40 = 20 meters ......Sell more flower cloth per day than it actually is 120 20 = 6 days ......Sold for 6 days 6 40 120 = 360 m ......The original stock flower cloth.

If the white cloth is x meters, the flower cloth is 2x meters.

set up to sell y days, then; 30y=x

40y+120=2x

It is obtained by two formulas; x=180

So the flower cloth is 360 meters.