Math problems don t want to ask for advice

If the size of a piece of land is taken as 1, then Xiao Ming shovels one-twelfth of the size of snow per hour, Xiaohong is one-eighth, Xiaojun is one-sixth, and Xiaofang is one-quarter. If everyone shovels together, the area to be shoveled in one hour is (1 12 + 1 8 + 1 6 + 1 4) = 5 8

That is, the area shoveled per hour is 5 8And the total area is 1So the time it takes is divided by one by five-eighths, and the answer is 8 5 hours, or hours.

This type of problem usually involves setting the total number to be completed to one and dividing it by the sum of everyone's efficiency.

The same piece of land. Xiao Ming took 12 hours and Xiao Hong took 8 hours. The small army took 6 hours. Xiaofang took 4 hours.

Find their least common multiple (for the convenience of later calculations), which is titled 24 hours.

In 24 hours: Xiao Ming got 2 plots of land, Xiaohong got 3 plots of land, Xiao Jun got 4 plots of land, and Xiao Fang got 6 plots of land.

Then they worked together for 24 hours and got a total of 2 + 3 + 4 + 6 = 15 plots of land.

It took 24 15 = 8 5 = hours to get a piece of land together.

Xiao Ming took 12 hours and Xiao Hong took 8 hours. The small army took 6 hours. Xiaofang took 4 hours.

They can each complete 4,1 (1 12+1 8+1 6+1 4)=24 15=hours per hour.

Considering the total amount of tasks as "1", first find out the work efficiency of each of them per unit of time, that is, how much is completed per hour.

Xiao Ming completes 1 12 of the total per hour;

Little Red completes 1 8 of the total amount per hour;

The small army completes 1 6 of the total per hour;

Xiao Fang completes 1 4 of the total amount per hour.

The four of them work together to complete the task, and they can complete a total of 1 12 + 1 8 + 1 6 + 1 4 = 15 24 5 8 per hour

The time required to complete the task is: 1 5 8 8 5 hours).

Summary. Okay, put 4 balls in it, that will make the water rise, then the volume of the water rising is the volume of 4 small balls.

Okay, it's fine.

Sixth grade. Well, you can describe the title, or send a **.

17 questions. Okay, I'll write down the process on paper, you wait a minute<> okay thank you. Does the title say how much to take?

Can you see death clearly?

I made a typo and I'm sorry to <>

Can you see it clearly, if you don't understand, you need me to explain it.

Let's explain it<>

Thank you. Okay, put 4 balls in it, that will make the water rise, then the volume of the water rising is the volume of 4 small balls.

The rising water column is also a small cylinder.

Then according to the formula of the volume of the cylinder r, multiply the square by the height, which is the height of the water column rising 2 centimeters.

This volume is divided by 4 and you get the volume of each ball.

Hello, I believe you should have understood, please give a thumbs up, thank you, and finally wish you a happy life.

(1) The probability of all three mothers finding their children is: 1 3 * 1 2 = 1 6

Description: The probability of the first mother finding her child is 1 3, and the probability of the second mother finding her child is 1 2

After the first two mothers were found, the remaining child was the third mother's child.

Therefore, the probability that all three mothers will find their child is 1 6

2) The probability of a mother finding her child is: 1 3*1 2 = 1 6

There happened to be one, understandably only one mother who found her child.

The probability that the first mother will find her child is 1 3, and the probability that the remaining two mothers will find each other's child is 1 2So, it just so happens that the probability of the first mother finding her child is 1 2*1 3=1 6

Similarly, the probability that the second mother and the third mother happen to find their child is 1 6.

So, the probability of a mother finding her child is 1 6+1 6+1 6=1 2

It can also be analyzed in this way: except for all three mothers who found their children and all mothers who found their children wrongly, the rest of the situation is that only one mother has found her child (it is impossible for two to find their own child, and the third is not their own child).

The probability that all three mothers can find their child is 1 6, and the probability that all three mothers cannot find their child is 2 3*1 2 = 1 3

So, the probability of exactly one mom finding her child is 1-1 6-1 3=1 2

3 2 There are 6 cases in total.

1) One-third one-half = one-sixth.

The first mother has a 1 in 3 chance of finding her child, and the second mother has a 1 in 2 chance of finding her child.

2) It is possible for every mother to find her child, there are 3 kinds in total, 3 6 = 1 in 2.

Friend, this is a very simple question, and it is a problem discussed in probability theory. But you give one less condition: that is, for a single mother, the probability of finding her child.

Assuming that this probability is p, then the probability that all three mothers will find their child is the product of the three p's, i.e., p*p*p. There happens to be a mother who finds the child, and there are three possibilities (because there are three mothers). Using the principle of probability theory, the probability is:

3*p*(1-p)^2。Explanation: 3 means that there are three situations, p means that one mother can find it, 1-p can not find the surface water, and there are two mothers who can't find it so they need to be squared.

Because you want to square (x-2), you have to have a 4, and there is a 2 in front of it, so there is an extra 8, and you want to keep the value the same, so you have to subtract an 8,

Big brother, add a 4 in parentheses, write it in a completely flat way.

Question 1: If the inventory of warehouse A is 4x, then the inventory of warehouse B is 5x. Then 5x-4x= solution x=.

So warehouse A is now in stock. B is 12. then two-fifths of the time.

A warehouse is. B for. Divide by two-fifths respectively to get 240,000 kilograms in the warehouse A.

Warehouse B is 260,000 kilograms.

Question 2: There are three classes of x, y, and z. Then the question is derived from (x+z 2):(y+z 2)=7:8.". x+5/8z=y+3/8z

From the second formula, x=y-1 4z is brought into the formula. It can be solved that y:z=11:2

Question 3: If the same ** is x, then the ** of the profitable product is x. The original price of the item at the loss is x. The profit is x * i.e. the loss is 1 12

Question 4: It takes x days to set up a armor. B takes y days. Then 1 x+1 y=1 18 3 x+4 y=1 5 gives y=30 x=45.

Rainy moon month, I will do the equation, but I want you to use your own brain and calculate 1Someone's buying a TV is actually very simple, grasp the conditions, express it in equations, and the problem will be solved. 1.You may want to set it up.

Warehouse problem: Warehouse A originally had x kg of grain, and warehouse B originally had y kg of grain, and according to the title, there were:

1-2 5)x: [(1-2 5y)+10,000]=4:5[(1-2 5y)+10,000]-(1-2 5)x=10,000 solution equations, the answer x and y values can be obtained;

The other topics are basically the same, nothing more than using known conditions to list equations and then solve the equations, which I will do a few more times, so I won't say more.

The sum of numbers that are opposite to each other is zero a+2b=0

A = -2b because b 0, 1 a exists = -1 2b choose a

There are six rooms for boys and five rooms for girls.

It should be the minimum.

The function y=(x+2)(x-1)=x2+x-2According to the vertex coordinate formula, its ordinate is the minimum value of y.

Min = (4ac-b2) 4a = -9 4

Both of them upstairs are wrong! Derivative first, we get that there are two extreme points, minus 2 and minus 4 5 have maxima at 2, bring into the original formula, and the result is 0