Knowledge point 1, fractional addition and subtraction application problem The application problem of fractional addition and subtraction is basically the same as the application problem of integer addition and subtraction in structure, quantitative relationship and problem solving method. The only difference is that it contains scores in known numbers or unknowns.
Knowledge point 2. The application problem of fractional multiplication refers to the application problem of knowing a number and finding a fraction of it.
Features: known units? 1? Quantity and fraction, find the actual quantity corresponding to the fraction.
The key to solving the problem: accurately judge the unit? 1? The number of. Find the score corresponding to the required question, and then formulate it correctly according to the meaning of multiplying a number by a score.
Knowledge point 3, fractional division application problem to find a number is another number of fractions (or a few percent).
Features: Knowing one number and another, find the fraction or percentage of one number. ? A number? This is a comparison. Another number? This is a standard quantity. Find a fraction or percentage, that is, find their multiple relationship.
The key to solving the problem is to start with the problem and find out who is regarded as the standard number, that is, who is regarded as it? Unit 1? Whoever compares the number of the first unit is the dividend.
A is the fraction (percentage) of B: A is the comparative quantity and B is the standard quantity. Divide a by b ..
How much is A more (or less) than B (a few percent): A minus B is more (or less) or (a few percent) than B ... Relationship (A minus B)/B or (A minus B)/A.
Given the fraction (or percentage) of a number, find the number.
Features: Knowing an actual quantity and its corresponding score, how to find the unit? 1? The number of.
The key to solving the problem: accurately judge the unit? 1? The amount of the unit? 1? The quantity of x is regarded as the meaning equation of fractional multiplication or fractional division, but the known real corresponding to the fraction must be found accurately.
Quantity.
Knowledge point 4. Attendance and germination rate = number of germinated seeds/number of experimental seeds? 100%
Wheat flour yield = flour weight/wheat weight? 100%
Product qualification rate = number of qualified products/total number of products? 100%
Employee Attendance = Actual Attendance/Attendance? 100%
Knowledge point 5. Engineering problem is a special case of fractional application problem, which is closely related to integer operation. It is an applied problem to explore the relationship among total workload, work efficiency and working hours.
The key to solving the problem: treat the total amount of work as a unit? 1? Work efficiency is the reciprocal of working hours, and then the formula can be used flexibly according to the specific situation of the topic.
Quantitative relationship:
Total work = work efficiency? working hours
Work efficiency = total workload? working hours
Working hours = total workload? work efficiency
Total amount of work? Work efficiency = cooperation time
Knowledge point 6. Paying taxes means paying a part of the collective or individual income to the state at a certain tax rate according to the relevant provisions of various national tax laws.
The taxes paid are called taxes payable.
The ratio of taxable amount to various incomes (sales, turnover and taxable income) is called tax rate.
Money deposited in the bank is called principal.
The extra money paid by the bank when withdrawing money is called interest.
The ratio of interest to principal is called interest rate.
Interest = principal? Interest rate? time