How to write a math modeling problem for junior high school

Take your time. Xiao Wang bought 1000 shares of a company at ** price (** at the time of closing) at ** price (** at closing) per share last Friday, and in the next week's trading days, Xiao Wang wrote down the rise and fall of the ** daily **** compared to the previous day: (unit:

yuan) week. One.

Two. Three. Four. Five.

Change per share (RMB).

According to the above table questions:

How much is it per share on Tuesday?

What is the highest and lowest price of the week?

It is known that both **** and sell ** need to pay a transaction fee of 5/1000 of the transaction amount. If Xiao Wang sells all of them at **price** this Friday, what will be his profit?

Solution: (1) The ** price on Tuesday is 25 2 yuan shares) 2) **The most ** is 25 2 yuan shares).

**The lowest price is $25 2 shares).

3) Xiao Wang's income is: 27 1000 (1 5) 25 1000 (1 5).

1740 (yuan).

Xiao Wang's income this time is 1740 yuan.

1.According to the water condition data, the probability of flat water conditions in a certain place during the flood season is the general probability of high water conditions.

rate, the probability of a flood is . A construction site located on the riverside has drawn up three disposal plans for its large-scale construction equipment:

1) If it is shipped away, you need to pay 150,000 yuan for freight.

2) For dam protection, a dam repair fee of 50,000 yuan is required.

3) No precautions, no expenditure.

If option (1) is adopted, no loss will be suffered regardless of any water condition; If scheme (2) is adopted, only when a flood occurs, the equipment will be lost due to the collapse of the embankment; If scheme (3) is adopted, then no loss will be suffered when there is a flat water level, 2 million yuan will be lost due to the loss of part of the equipment when the high water level occurs, and 4 million yuan will be lost when the equipment is lost in the event of a flood. Based on the above conditions, the best decision-making scheme is selected.

Solution: We use mathematical expectations to judge the merits of the solution:

Ship away -15

No flooding -5

A-15 Dam repair B

Flood occurred -405

Flat water 0c high water -200

Flood -400

e(a)=-15

e(b)= 25

e(c)=0×

Therefore, -e(a)< e(b)< e(c), so that option A is the best decision-making option.

The types of mathematical modeling questions can be divided into the following categories:

Optimization problem: Jujube requires the design of an optimal scheme to make a certain index of guessing the bridge reach the maximum or minimum value, such as minimizing costs and maximizing profits.

Mathematical model construction questions: It is required to build a mathematical model based on practical problems, including determining variables, relationships, constraints, etc.

Stochastic Process Modeling Topics: Modeling and analysis of systems with randomness, such as Monte Carlo simulations, Markov chains, etc.

Graph theory problems: Graph theory methods are required to study problems, such as the shortest path and the smallest spanning tree.

Calculus problems: Requires the application of calculus principles to solve problems, such as extreme values, curve fitting, etc.

Linear algebra problems: Requires the application of linear algebra knowledge to solve problems, such as matrix inversion, matrix factorization, etc.

a.Mathematical classification of the model (what type it belongs to) bModeling ideas (ideas) c

Algorithmic ideas (solution ideas).

d.Modeling characteristics (model advantages, modeling ideas or methods, algorithm characteristics, result testing, sensitivity analysis, models.

Modeling is a process of solving problems, your model is the mathematical method of solving problems, if you are participating in the competition, it is recommended to see more excellent**, coordinate the division of labor of three people, and do more exercises.